Audio Research SP-11 MK2 ...

For classic equipment it is good.
Compared to the new stuff at way more money? No it is not.
"Top class" no. it is no longer 'top class'
It was made in 1985!! that is a pretty long time ago.

I own an Audio Research Sp-15, the model after the Sp-11 which still is a two chassis affair. (and it uses the same phono section of the Sp-11)
I keep it around to use it's phono section..
But as a preamp it is not as good as my new Bryston BP-26.

I also had an Audio Research Sp-10, and i am sorry but the Sp-15 killed the Sp-10 in nearly any way i could think of. And i gladly sold the Sp-10 for twice what i thought it was worth, but still $800 less than the average asking price!.(and selling the SP10 basically got me the Sp-15 for free) i will not be selling my Sp-15 anytime soon... Even though i hardly use it...
If you are paying $1,500 or so for one, then it is a fair deal.. a lot more money than that and it is an overpriced boat anchor.

Wow! that was really interesting. Before I purchased my REF 3, I retubed my SP-11 MKII with AR supplied tubes and I have to tell you I with several of my friends over about a week compared my borrowed REF 3 (dealer demo) with the retubed SP11 MKII and several other borrowed pre-amps from the dealer, including other AR pre-amps and the re-tubed SP11 MK II held its own quite nicely. We were hard pressed to hear major jaw dropping differences. There were differences and the REF 3 ultimately was a better pre-amp, but blown away? not close. Also, the re-tubed SP11 MK II actually was better than the newer AR pre-amps in our opinion. I tried hard to justify purchasing the REF 3 and made up many excuses, but keeping the SP11 MK II would not have been a mistake. I wanted a remote control pre-amp (getting lazy) and compared the SPII with several remote control units and not one justified the huge increase in cost. Not even the REF 3. I bought it anyway and it is great, but I really didn't need to do it. The gentleman that I sold the SPII to loves it also. I would say, re-tube the pre-amp with proper tubes from AR before getting rid of it. In my opinion, with all respect to Elizabeth, it is still one of the best out there. Re-tubed.

enjoy

I have had my SP-15 for about 10 years now. I sent it in to ARC in 2004 due to a bad umbilical cord and they refurbished it while it was there by replacing all of the electrolytic caps in the power supply. About a year and a half ago, I bought some NOS tubes for the phono section. The difference in sound blew me away. I am still enjoying my vinyl as if new with these tubes. After my SP-15 has been on for about an hour, I can sit down and enjoy the music, but the music gets more fluid (best way I can describe it) after it has been on for 8+ hours. I have listened to the REF 5 with the REF ARC amps on a different system, so a bit out of context. Very nice sound, but I don't feel like I am missing anything. Good thing, or else I wouldn't be able to sleep until I found a way to aquire the REF 5. As for remote; that's what the kids are for...

I owned an SP-11 mk II for a number of years. In its time it was one of the best preamplifiers available, and it gave me a lot of pleasure. It is still good, but I believe it to be surpassed by the better preamps out there now (I replaced it around 1990 with a Jadis JPL/Vendetta SCP-2B combination, as the tubed JPL was more to my liking and the Vendetta was a quieter and better phono stage than the ARC's). It is not really as liquid or dimensional as a great tube preamplifier, and its solid state circuitry is not as good as more recent mainly solid state preamplifiers I have heard, like the Lamm L2 (the tube in that unit is in the power supply) and Boulder units. It's very good as far as vintage equipment goes, as Elizabeth says, and it does have some very useful features that you don't find in modern units (especially for listening to vinyl, including a mono switch and a knob in the front for some cartridge loading). I have found it interesting that it does not seem as prized in the used market as the SP-10 that it replaced in the ARC line.