Listing Includes: O2 Headphone Amp AC power adapter rca cables 2 9v rechargeable batteries (installed) Grace Designs SDAC usb cable MASSDROP OBJECTIVE 2 HEADPHONE AMP: DESKTOP EDITION In 2011, audio engineer NwAvGuy published a blog post titled “O2 Headphone Amp,” in which he outlined his philosophy on defining sound quality and detailed his ideal audiophile circuit design. Our version of NwAvGuys famous O2 amplifier, the Objective 2 Desktop Edition features updates based on feedback from the community. It’s an ideal baseline reference amplifier, capable of powering everything from IEMs to HD 800s with linear ease. SPECSInput: RCA Output: 6.35 mm Power: Battery (included) or AC adapter (included)Gain: 2.5x and 6.5x / 1.0x and 3.3x (select your configuration)Volume potentiometer taper: Alps 15A or 3BFrequency response: +/-0.1 dB (20 Hz–20 kHz)THD at 1 kHz, 150 ohms: 0.0016%IMD CCIF at 15 ohms: 0.001%IMD SMPTE: 0.002%Noise (ref 400 mV): -105 dBMax output (33 ohms): 613 mWMax output (150 ohms): 355 mWMax output (600 ohms): 88 mWOutput impedance: 0.54 ohmsCrosstalk (15 ohms): -65 dBChannel balance (50% volume): 0.6 dBCase dimensions: 4.12 x 3.87 x 1.12 in (10.46 x 9.82 x 2.85 cm)Weight: 9 oz (255 g)INCLUDED110V AC adapter 2 - 9v rechargeable batteries (installed) RCA Cable MASSDROP X GRACE DESIGN STANDARD DAC Made in collaboration with Grace Design, a company known for its incredibly accurate, transparent studio gear, the Standard DAC sets a new standard in entry-level DACs. It applies Grace Design’s pro-audio expertise to a simpler, more accessibly priced model that makes a great addition to any home or office system. Designed with the objectivist audiophile in mind, the SDAC delivers objectively good performance meant to meet or exceed the measurements of the popular ODAC while retaining many of its other benefits. Compact, capable, and easy to use, it could be all the DAC you need. SPECSMassdrop x Grace DesignChassis material: Anodized aluminumDAC chip: AKM AK4452Audio formats: Up to 24 bit/96 kHzFrequency response, 20Hz–20 kHz: +/-0.02 dBTHD+N at 20 Hz -0.15 dBFS: 0.0013%THD+N at 100 Hz, -0.15 dBFS: 0.0013%THD+N at 10 kHz, -0.15 dBFS: 0.0024%IMD CCIF, -6.03 dBFS, 19/20kHz, 24/96k: 0.0005%IMD SMPTE -6 dBFS, 24/96k: 0.0015%Noise, A-weighted: -105 dBuDynamic range, A-weighted: >114 dBLinearity, -90 dBFS: -0.07 dBCrosstalk at 1 kHz, -10 dBFS (3.5mm jack): -102 dBSum of jitter components at 11,025 Hz, -1 dBFS: -133 dBMaximum output: 2.15VRMSUSB controller: XMOS XU208-128-TQ64Inputs: USB microOutput: ? in (3.5 mm) TRS, RCAPower: USB Class 1 (no drivers required for Windows, Mac, or Linux)Dimensions, L x W x H: 3.9 x 4.1 x 1.2 in (100 x 104 x 30 mm)Length with RCA port: 4.2 in (105.5 mm)Height with rubber feet: 1.4 in (34 mm)Weight: 7.44 oz (210.8 g)

Massdrop x Alex Cavalli Liquid Carbon X amp, built by the founder of Cavalli Audio—a legend in the world of headphone amps. For the DAC section, it uses the Massdrop x Grace Design Standard DAC (or SDAC), a collaboration with a company long known for its incredibly accurate, transparent studio gear. The Liquid Carbon X is a solid-state, fully balanced, bridged amp with a clear, transparent, non-fatiguing sound. It has the same topology as the celebrated Liquid Carbon, along with updates to the form factor, switching power supply, and input and output jacks. The four amplifier sections—two per channel—create a clean, distortion-free signal and a quiet background. It retains the Liquid Carbon’s single-ended output for convenience with unbalanced cables, and also has a balanced output for when you need more power and ultimate performance. The Liquid Carbon X adds a protective offset detector, and for quieter operation and compatibility with worldwide voltages, moves the power supply out of the chassis. Plus, you can adjust the gain on the front panel for different headphones. The Standard DAC sets a new standard in entry-level DACs. Designed with the objectivist audiophile in mind, the SDAC delivers objectively good performance meant to meet or exceed the measurements of the popular ODAC while retaining many of its other benefits. It’s equipped with the new AKM AK4452 digital-to-analog conversion chip and can process the most common file types up to 24 bit/96 kHz with no harshness or edge and the kind of resolution and detail that’ll make you want to listen on and on. It runs off of USB bus power with plug-and-play operation, which means you won’t need drivers or any special software to get started.

A Portable Headphone Amp with Impeccable Sound Grace Designs m900 takes the stunning detail and flawless imaging of their flagship m920 headphone amplifier and packs it into a portable, bus-powered unit. But just because the m900 is portable, doesnt mean its lacking. Experience jitter-free computer audio playback, with support for up to 32-bit/384kHz PCM and 256x DSD. Dual zero-ohm output impedance headphone outputs deliver spacious and transparent performance, while stereo unbalanced analog outputs make connecting to your stereo monitor system easy. Either way, four different DAC filter settings provide personalized playback. At Sweetwater, we appreciate the m900s simple setup menu and easy-to-read 7-segment LED display, and its large rotary encoder makes volume control and menu navigation a breeze.Grace Design M900 Features: 2-ch headphone amplifier and top-shelf D/A converter Portable bus-powered unit is ideal for travel, desktop, or studio Jitter-free computer audio playback with support for up to 32-bit/384kHz PCM and Sweetwater is an Authorized Grace Design Dealer Genuine Open Box Item Sweetwaters 2-year warranty Grace Design m900 - Desktop DAC Headphone Amplifier 2-ch Headphone Amplifier with Stereo Unbalanced Analog Outputs, Digital Input via USB, TOSlink, and S/PDIF Coax, and Support for 44.1kHz-384kHz PCM and 64X-256X DSD Audio - Mac/PC A Portable Headphone Amp with Impeccable Sound Grace Designs m900 takes the stunning detail and flawless imaging of their flagship m920 headphone amplifier and packs it into a portable, bus-powered unit. But just because the m900 is portable, doesnt mean its lacking. Experience jitter-free computer audio playback, with support for up to 32-bit/384kHz PCM and 256x DSD. Dual zero-ohm output impedance headphone outputs deliver spacious and transparent performance, while stereo unbalanced analog outputs make connecting to your stereo monitor system easy. Either way, four different DAC filter settings provide personalized playback. At Sweetwater, we appreciate the m900s simple setup menu and easy-to-read 7-segment LED display, and its large rotary encoder makes volume control and menu navigation a breeze.Grace Design M900 Features: 2-ch headphone amplifier and top-shelf D/A converter Portable bus-powered unit is ideal for travel, desktop, or studio Jitter-free computer audio playback with support for up to 32-bit/384kHz PCM and 256x DSD Dual zero-ohm output impedance headphone outputs deliver spacious and transparent performance Stereo unbalanced analog outputs make connecting to your stereo monitor system easy Compatible with a wide variety of digital sources via USB, TOSlink, and S/PDIF coax 4 different DAC filter settings provide personalized playback Simple setup menu and easy-to-read 7-segment LED display Large rotary encoder for easy volume control and menu navigation SpecificationDetail Type Headphone Amp & DA Converter Input Channels Stereo Output Channels 2 Analog Outputs 2 x RCA (stereo) Headphones 2 x 1/4 TRS Digital Inputs 1 x Coax (S/PDIF), 1 x Optical Toslink USB 1 x Micro-B (high power), 1 x Micro-B (data, bus power) Form Factor Portable Power Supply USB bus powered Height 1.8 Width 4 Depth 5.25 RETURN INFORMATION We want you to be completely happy with your purchase from Sweetwater. If you are not satisfied with your product, you may return it for a refund of the purchase price within 30 days. If your purchase was eligible for Free Shipping, the shipping cost will be deducted from your credit or refund. Returns must be in the complete and original packaging with all accessories and complete documentation (Owners Manual, warranty card, quick start guides, etc.), show no signs of wear or use, and include a Return Authorization number or be subject to a restocking fee. Fast, FREE Shipping! Nearly every order received by 3PM Eastern ships the SAME DAY! FREE shipping to lower 48 states. Our central location reaches most states in 1-4 business days 99.95% warehouse accuracy We are proud to provide some of the fastest turnaround times on eBay. We use FedEx or UPS for most items, and USPS for smaller items. Residents of Hawaii, Alaska, and Puerto Rico should contact us for a shipping quote. PLEASE NOTE: We cannot ship large items to PO boxes, please provide an alternate address. If you have questions, feel free to contact us. Buy with confidence! Sweetwaters been selling on eBay since 2001, with 99.9% positive feedback! More than 30 years in business World-class customer service Fast, FREE shipping Free 2-year warranty on nearly every product Free tech support from audio experts

Condition: Untested and sold as-is. No testing has been done Disclaimer: Item appears to power on or have operable mechanisms in brief testing. It has not been further tested for functionality in any capacity and functionality is not guaranteed. This is a used, donated item that has not been cleaned, serviced or tested for functionality. Unless otherwise stated, items have not been inventoried for completeness. We generally perform power on and basic functional tests on all of our used items. Items with Parts and repair status are either incomplete for parts or has defects that requires expert repairs. Please make sure to check for compatibility before purchase.We will try to provide the best detail on items we sell. Please keep in mind that since all of our listed items are donated, most likely we will not have any background and functional history for them. Please refer to pictures for more additional information. Please contact us via the eBay message system if you have any questions. _____________________________________________________________________________________________________ Thank you for shopping with SF Goodwill! Your generous purchase from Goodwill makes a big difference for local people struggling with unemployment. Your purchase funds job programs and services for people overcoming challenges like homelessness, former incarceration, lack of job skills and limited education. We create second chances through training and the dignity of work. Payment: ??????Payments are due within 7 days from auction end date. Shipping: ??????We do not ship to PO Boxes or Military Addresses (ie: APO/FPO/DPO/etc) Combined Shipping: Yes, We Offer Combined Shipping Discounts! Item with the highest shipping price will be billed at full price shipping, additional items: 75% off each shipping cost Most orders qualify for an automatic combined shipping discount, simply check out and pay! Some items cannot be combined in shipping (fragile, oversize or heavy items) We cannot apply a combined shipping discount after payment has been made Please send us a direct message if you need help, or require a custom combined shipping invoice. Local Pickup: Were offering local pickup effective 11/1/2023. Once the auction has ended, choose the local pickup option during checkout. If you have any issues choosing local pickup, please let us know. Once checkout via local pickup has been completed, please allow 24-48 hours to contact you and schedule your order pickup. Local Pickup is by appointment only. We will not accept on the spot pickups. Orders must be picked up within 7-days of the scheduled appointment. Pickup extensions will not be offered. Contact us for the local pickup instructions. Order Issues and Questions: Problems with your order? Were here to help! Please contact us via the eBay message system if you have any issues with your order. Due to our high volume of sales, please allow 24-48 hours for us to respond to your messages. ______________________________________________________________________________________________________ Our Mission: Each year, nonprofit Goodwill of San Francisco, San Mateo and Marin breaks the cycle of poverty for thousands of local people through our transformative free training and work placement programs. Goodwill serves anyone who comes through our doors with a willingness to work. Job Creation: From skills training to job coaching that leads to employment, we identify and develop job-readiness skills on both a personal and professional level, plus offer a variety of employment support services. Employment at Goodwill: Our 21 retail stores, 25 attended donation centers and 2 warehouses employ more than 600 people and provide training and employment opportunities for individuals seeking to learn and build work skills that lead to career pathways. Employment with Top Bay Area Companies: Our experienced employment coaches connect work-ready job seekers with open positions at a range of companies throughout San Francisco, San Mateo and Marin counties. Impacts: Last year, Goodwill of San Francisco, San Mateo and Marin placed our participants in 636 jobs and transitional employment opportunities. In addition, education, job training, and employment services were provided to 3,200 people in our three-county region, and 10,300 visits were made to our Comprehensive Access Point Job Center.

Massdrop x Alex Cavalli Liquid Carbon X amp, built by the founder of Cavalli Audio—a legend in the world of headphone amps. For the DAC section, it uses the Massdrop x Grace Design Standard DAC (or SDAC), a collaboration with a company long known for its incredibly accurate, transparent studio gear. The Liquid Carbon X is a solid-state, fully balanced, bridged amp with a clear, transparent, non-fatiguing sound. It has the same topology as the celebrated Liquid Carbon, along with updates to the form factor, switching power supply, and input and output jacks. The four amplifier sections—two per channel—create a clean, distortion-free signal and a quiet background. It retains the Liquid Carbon’s single-ended output for convenience with unbalanced cables, and also has a balanced output for when you need more power and ultimate performance. The Liquid Carbon X adds a protective offset detector, and for quieter operation and compatibility with worldwide voltages, moves the power supply out of the chassis. Plus, you can adjust the gain on the front panel for different headphones. The Standard DAC sets a new standard in entry-level DACs. Designed with the objectivist audiophile in mind, the SDAC delivers objectively good performance meant to meet or exceed the measurements of the popular ODAC while retaining many of its other benefits. It’s equipped with the new AKM AK4452 digital-to-analog conversion chip and can process the most common file types up to 24 bit/96 kHz with no harshness or edge and the kind of resolution and detail that’ll make you want to listen on and on. It runs off of USB bus power with plug-and-play operation, which means you won’t need drivers or any special software to get started.

Grace m900 Digital Audio Unit - https://www.sweetwater.com/store/detail/M900--grace-design-m900-desktop-dac-headphone-amplifier NEVER OPENED this one and I missed the return window. So passing on some savings to you.Grace Designs m900 takes the stunning detail and flawless imaging of their flagship m920 headphone amplifier and packs it into a portable, bus-powered unit. But just because the m900 is portable, doesnt mean its lacking. Experience jitter-free computer audio playback, with support for up to 32-bit/384kHz PCM and 256x DSD. Dual zero-ohm output impedance headphone outputs deliver spacious and transparent performance, while stereo unbalanced analog outputs make connecting to your stereo monitor system easy. Either way, four different DAC filter settings provide personalized playback. At Sweetwater, we appreciate the m900s simple setup menu and easy-to-read 7-segment LED display, and its large rotary encoder makes volume control and menu navigation a breeze. Good video information on the m900 here: https://www.youtube.com/watch?v=AdK0E1YJx4M

A Portable Headphone Amp with Impeccable Sound Grace Designs m900 takes the stunning detail and flawless imaging of their flagship m920 headphone amplifier and packs it into a portable, bus-powered unit. But just because the m900 is portable, doesnt mean its lacking. Experience jitter-free computer audio playback, with support for up to 32-bit/384kHz PCM and 256x DSD. Dual zero-ohm output impedance headphone outputs deliver spacious and transparent performance, while stereo unbalanced analog outputs make connecting to your stereo monitor system easy. Either way, four different DAC filter settings provide personalized playback. At Sweetwater, we appreciate the m900s simple setup menu and easy-to-read 7-segment LED display, and its large rotary encoder makes volume control and menu navigation a breeze.Grace Design M900 Features: 2-ch headphone amplifier and top-shelf D/A converter Portable bus-powered unit is ideal for travel, desktop, or studio Jitter-free computer audio playback with support for up to 32-bit/384kHz PCM and Sweetwater is an Authorized Grace Design Dealer Genuine Open Box Item Sweetwaters 2-year warranty Grace Design m900 - Desktop DAC Headphone Amplifier 2-ch Headphone Amplifier with Stereo Unbalanced Analog Outputs, Digital Input via USB, TOSlink, and S/PDIF Coax, and Support for 44.1kHz-384kHz PCM and 64X-256X DSD Audio - Mac/PC A Portable Headphone Amp with Impeccable Sound Grace Designs m900 takes the stunning detail and flawless imaging of their flagship m920 headphone amplifier and packs it into a portable, bus-powered unit. But just because the m900 is portable, doesnt mean its lacking. Experience jitter-free computer audio playback, with support for up to 32-bit/384kHz PCM and 256x DSD. Dual zero-ohm output impedance headphone outputs deliver spacious and transparent performance, while stereo unbalanced analog outputs make connecting to your stereo monitor system easy. Either way, four different DAC filter settings provide personalized playback. At Sweetwater, we appreciate the m900s simple setup menu and easy-to-read 7-segment LED display, and its large rotary encoder makes volume control and menu navigation a breeze.Grace Design M900 Features: 2-ch headphone amplifier and top-shelf D/A converter Portable bus-powered unit is ideal for travel, desktop, or studio Jitter-free computer audio playback with support for up to 32-bit/384kHz PCM and 256x DSD Dual zero-ohm output impedance headphone outputs deliver spacious and transparent performance Stereo unbalanced analog outputs make connecting to your stereo monitor system easy Compatible with a wide variety of digital sources via USB, TOSlink, and S/PDIF coax 4 different DAC filter settings provide personalized playback Simple setup menu and easy-to-read 7-segment LED display Large rotary encoder for easy volume control and menu navigation SpecificationDetail Type Headphone Amp & DA Converter Input Channels Stereo Output Channels 2 Analog Outputs 2 x RCA (stereo) Headphones 2 x 1/4 TRS Digital Inputs 1 x Coax (S/PDIF), 1 x Optical Toslink USB 1 x Micro-B (high power), 1 x Micro-B (data, bus power) Form Factor Portable Power Supply USB bus powered Height 1.8 Width 4 Depth 5.25 RETURN INFORMATION We want you to be completely happy with your purchase from Sweetwater. If you are not satisfied with your product, you may return it for a refund of the purchase price within 30 days. If your purchase was eligible for Free Shipping, the shipping cost will be deducted from your credit or refund. Returns must be in the complete and original packaging with all accessories and complete documentation (Owners Manual, warranty card, quick start guides, etc.), show no signs of wear or use, and include a Return Authorization number or be subject to a restocking fee. Fast, FREE Shipping! Nearly every order received by 3PM Eastern ships the SAME DAY! FREE shipping to lower 48 states. Our central location reaches most states in 1-4 business days 99.95% warehouse accuracy We are proud to provide some of the fastest turnaround times on eBay. We use FedEx or UPS for most items, and USPS for smaller items. Residents of Hawaii, Alaska, and Puerto Rico should contact us for a shipping quote. PLEASE NOTE: We cannot ship large items to PO boxes, please provide an alternate address. If you have questions, feel free to contact us. Buy with confidence! Sweetwaters been selling on eBay since 2001, with 99.9% positive feedback! More than 30 years in business World-class customer service Fast, FREE shipping Free 2-year warranty on nearly every product Free tech support from audio experts

Grace m900 Digital Audio Unit - https://www.sweetwater.com/store/detail/M900--grace-design-m900-desktop-dac-headphone-amplifier NEVER OPENED this one and I missed the return window. So passing on some savings to you.Grace Designs m900 takes the stunning detail and flawless imaging of their flagship m920 headphone amplifier and packs it into a portable, bus-powered unit. But just because the m900 is portable, doesnt mean its lacking. Experience jitter-free computer audio playback, with support for up to 32-bit/384kHz PCM and 256x DSD. Dual zero-ohm output impedance headphone outputs deliver spacious and transparent performance, while stereo unbalanced analog outputs make connecting to your stereo monitor system easy. Either way, four different DAC filter settings provide personalized playback. At Sweetwater, we appreciate the m900s simple setup menu and easy-to-read 7-segment LED display, and its large rotary encoder makes volume control and menu navigation a breeze. Good video information on the m900 here: https://www.youtube.com/watch?v=AdK0E1YJx4M

Grace m900 Digital Audio Unit - https://www.sweetwater.com/store/detail/M900--grace-design-m900-desktop-dac-headphone-amplifier NEVER OPENED this one and I missed the return window. So passing on some savings to you.Grace Designs m900 takes the stunning detail and flawless imaging of their flagship m920 headphone amplifier and packs it into a portable, bus-powered unit. But just because the m900 is portable, doesnt mean its lacking. Experience jitter-free computer audio playback, with support for up to 32-bit/384kHz PCM and 256x DSD. Dual zero-ohm output impedance headphone outputs deliver spacious and transparent performance, while stereo unbalanced analog outputs make connecting to your stereo monitor system easy. Either way, four different DAC filter settings provide personalized playback. At Sweetwater, we appreciate the m900s simple setup menu and easy-to-read 7-segment LED display, and its large rotary encoder makes volume control and menu navigation a breeze. Good video information on the m900 here: https://www.youtube.com/watch?v=AdK0E1YJx4M

This is a personal DAC/amp I purchased from Massdrop (DROP) who collaborated with Grace Designs back in 2016. Its a great desktop DAC/amp but I never really used my headphones for computer streaming all that much. I probably used this DAC maybe a couple of dozen times at best. Massdrop/DROP had a very limited run of these DACs and are no longer sold. The m900 is closest thing currently to the m9XX. Exterior is in overall very good condition. There is a tiny ding/marring on the top left side of the case. Unfortunately that was how it was like when I received it. It didnt bother me all that much since it was a small imperfection. I have included a Samsung 5V-2A Fast Travel Charger - THE ORIGINAL POWER ADAPTER AND MICRO USB CABLES ARE NOT INCLUDED. You will need a pair of Micro-USB Cables to operate the DAC: one for power and for connectivity to your source. Or you can use a Toslink for A/V connectivity. Well reviewed on Head-Fi, HiFi Insider, and beyond, the Massdrop x Grace Design m9XX was inspired by the world-class m920 DAC/amp—offering the same performance level for audiophile applications, now at a far more accessible price. Working with Michael and Eben from Grace Design, we stripped the m920 of its lesser-used pro audio hardware and improved upon the audiophile features where possible, all while retaining the high-res DAC implementation and super-clean solid-state amplification. The result? A portable, affordable, and sleek piece of gear; one that benefits from Grace Design’s decades of expertise in analog circuitry and better serves the needs of the audiophile community. You can get more detail through the Drop link: https://drop.com/buy/grace-design-x-massdrop-m9xx-dac-amp All sales final. No returns accepted. Shipping rates will vary depending on destination. Additional insurance is recommended.