Audio Research Preamp. It works but there’s a buzz/hum in both channels, it will get louder with increased gain. I can’t seem to figure it out. Selling as-is. For parts or repair.

I have for sale some very rare Audio Research gold plated, machined metal knobs. These are (new old stock) knobs that were in storage for a number of years and have never been installed in equipment. The overall condition of the knobs is very good. Two of the knobs have some minor scratchs on the side which is only noticeable on close examination. The knobs are from the estate of an Audio Research employee. Im selling (4) knobs in my ad as pictured, The knobs will fit any Audio Research preamplifier that starts with an SP and take 4 knobs. Such as the Audio Research SP-4, SP-5, SP-6, SP-7, SP-8 SP-9, Note: The knobs will not fit the Audio Research LS series of line stage preamplifiers. One thing worth mentioning...the knobs have a shiny gold surface, so its very hard to get a good picture of one knob or a group of knobs. If you are unsure if the knobs will fit in your Audio Research piece of equipment, please email me before buying the knobs. Continental USA shipping only, No International sales.