This is an outstanding sounding Audio Research SP6 preamp. I've had it for about 7 years, and I rebuilt it about 6 years ago. It is totally reliable, and sounds incredible.
During the time I've had it, I also had an SP8 mk II, which I had refurbished and tweaked, and an SP3 I also massively upgraded with Curcio power supply regulated boards, better caps, etc. I also had a legendary EAR 802 preamp. The SP6 was and is head and shoulders above them, and I kept it, while selling the EAR, the SP8 and the SP3.
This SP6 has also been modded prior to my ownership, and already sounded very good. There is a plaque at the back - it was modded by Eagle Audio (Gas works as in Ampzilla?). The white capacitors on the bottom, both in the phono and line stages, are left over from this upgrade. The black goop is to hide what the cap was from inquisitive eyes and competitors - looks like wondercaps!).
My contributions to this amp were to more than double the power supply capacitors to Nichicon low ESR types, change selective diodes to ultrafast ones, and to change many capacitors to very good sounding Paper-in-oils, and Teflons. I also improved all the RCA jacks to gold plated ones. I also replaced the power cord with an IEC outlet.
I did not do any more work to the Phono stage, as it already sounded very good, especially after the power supply mods. To be much better, you need to move to a external phono stage, like the PH3 I am selling.
These changes made a very good amp sound even better. I use it in a system with 4 Quad ESL63s, and it is just very natural sounding and musical.
I also tracked down a very rare wood case for this amp, and it looks wonderful.
The top and bottom plate are pretty beat up - that was how I got it. I'm also missing some of the screws. However, once you put the wood case on, you can't see any of this stuff. There are a couple of light scratches on the face plate.
So, you might ask, if this is a keeper, why am I selling it? Well, I don't really want to sell it, but if you see my other ads, I also have 2 other great preamps for sale as well - an ARC LS5, and a Croft (and some more that are backups, and that I might at some point I will try and upgrade). I certainly don't need all 3, just 1 of the 3. So, I'll keep whichever of the 3 don't sell - they are all reference quality and will do the Quads system justice.
I am including my favorite standard tubes - Shuguang 12ax7c. The sound from this preamp can be improved a little more by using vintage Telefunken or Seimens 12ax7 - I have some I can supply at extra cost. (I don't typically use them as this is not in my primary system, and the Shuguangs are very good).
Whoever buys this is going to get a steal. All the SP6s and SP8s on ebay, have usually not been updated, let alone upgraded with all these mods. This one will sound better than them, and last a lot longer too!
I will only accept Paypal, and expect immediate payment. Shipping will be by insured Fedex.