Audio Research SP15 sonics

I don't find much info. about the SP 15 preamp as I do the popular SP10 and SP11. Weigh in, please, with opinions of the SP15s reputation? I'm considering a purchase.
The SP15 was the successor to the SP11 in its line of hybrid preamps. The 15 used far less tubes than the 11--it was more a solid-state hybrid than a tube hybrid, like the SP11, and to my ear it sounded that way. I heard it often at my dealer's while I owned my SP11, and I just never warmed to it--if I had owned an SP10 at the time I probably would not have liked it at all. Definitely a very clean sound, but to my ear it was too clinical and analytical (probably more accurate, though), and brighter, more lacking in tonal color, than the SP11. I guess you could say I respected it but didn't love it. It is a value given its phono stage over the later ARC line stages, but I'd prefer an LS5 over it sonically, as well as the 10 and 11.

The SP-15 is one of my favourite pre-amps. Compared to other pre-amps, there's a lack of colouration and the phonostage is awesome. The SP-10 and 11 are coloured pre-amps, just like the 'nice' Conrad-Johnson Premier 3 was. Maintenance-wise the SP-10 is a bad choice (too many tubes and excess heat). Comparisons with the LS-series amps are nonsense, since these were made (much) later.
You should combine the SP-15 with a decent solid state power amp and good speakers, such as Quads '63 on very high stands and of course a decent source, such as a Goldmund or similar turntable. Then you're in for a sensation, voices are splendid. Do not connect mid-fi, you will surely be disappointed.
I will probably buy a good set myself someday to 'relive' the old memories.
I have a SP-15 which I had upgraded by removing all the factory caps and replacing them with MIT Multicaps.

You can not imagine what a world of difference it made!!
Like a different pre-amp! The mod was done by the "famous" George Kaye (Mr. Moscode) when he was in NYC...he is now located in Holyoke, Mass. he has a Web site.
You should contact him if you are serious about upgrading your SP-15.
Hi all SP15 users,

I just got myself a 2nd hand SP15 and it sounds awesome. However the Sp15 doesn't come with a user/owner/service manual (whatever they call it), is it possible to get hold of a copy, photocopy is ok.

many thanks.