Unique little (6.75 x 4.75 x 1.75) integrated amp from 2014 intended mainly for use with audio from computers and such. Puts out 20 watts/channel using a Tripath chipset. I purchased it new around that time intending to use it for a kids dorm room setup but they had other ideas so I put it away until now. Has a real power cord (no wall wart) and two digital inputs - one USB and one Toslink (optical). There is no input switch...the unit defaults to whichever input is playing. I provide a short USB-B to USB-A cable (ideal for connecting to desktop or laptop). The Toslink optical input is a 3.5mm mini-jack type requiring a Toslink-to-3.5mm adapter (NOT PROVIDED - not sure what happened to it). I tested the amp using the USB input and it worked fine. Nice machined aluminum case. The reason it has a volume control on/off switch on the back is because it can be daisy chained with other Musical Fidelity V90 products (e.g., DAC) and you may not want two volume controls in the system. If using stand alone, leave this switch on. Power on/off is done by pushing on the volume control knob. Bottom line is if youre looking for a well-made, nice-looking, small 2-channel amp for your tiny system/computer desk, this will work well. Be mindful of matching this with the appropriate speakers. These were over $300 when originally available.