I'd like to tell my assessment on all the preamps I have owned to date, lined up from the best to the so so and to the worst:
BEST List
1. McIntosh C11 (Absolute best to me for vinyl and CD, both. It is a C22 in another dressing. Its best feature was stepped tone adjustment, and LP/RIAA EQ switch.)
2. Audio Research SP-3 (Closest second best to the C11. Clear highs and stunning transparency, low noise, involving soundstage and details, also deep bass FR. Provides tone off switch, but tubes V4-V5 removable if tone unused. And absolute support from ARC with parts and updates still available. Sounds absolutely neutral yet dynamically involving and impactful when playing orchestral music, superb soundstage and holographic imaging. The best tubed phono stage in this list, on par with the Nak CA-7. Channel and tonal balances are easy to achieve with brief tube-rolling. Often sold used today at 3 times its original cost of arnd 500 USD. Still appreciating even in CL. It has the level of charm to make itself stay in my main system long-term. Down-side: not as high-class as the luxuriant and beautifully lit C11.)
3. CV PV-8 Phono version (Non-NFB circuitry provides cleanest sound output, cool looks, great machining and design. Tho' a bit clinically sounding to my taste, contrary to ppl's views that it sounds coloured.)
4. McIntosh MX113 (The Phono and Line preamp parts) (Sounds even better than its C26 preamp sibiling on contrast, with rich tone, deep bass, good 3D presentation, despite details a bit squashed in comparison with the AI M3A mentioned below)
5. Audible Illusions M3A (Separate PSU, low noise, clean sound but not too clinical, versitility with cartridge choice, relatively cheap to buy. But, not cheap for long-term use due to possibly more frequent tube replacement of those half dozn premium 6DJ8/6922, still available a couple of dollars on taobao on the rigid 6H11N EB/EV or 6H1N EB/EV version
6. Nakamichi CA-7(A) (All discrete component design, great build, best MC and MM section with gain, capacitance and load choices, great remote control. Warm sound comparable to C11, The best sound stage of all in this list, let down only by too much clinical detail. Think of it as "gold in gold out, trash in trash out". Good to hold up to IMHO newly made preamps up to 10K USD.)
SO-SO List
7a. McIntosh C20 (It might hv been only I who placed this model in a so-so list. During an age when more meant better, it runs on 2 x 12AX7 for its phono stage, and 2 12AU7 on its tone stage, then another 2 x 12AX7 on line stage, followed by a buffer stage on 1 x 12ax7 shared btwn L/R channels. Tho' one 6X4 tube provides good clean power to it, yet, among my 3 examples of the C20, none can keep its channel balance today, implying parts spec drift affecting performance. More so than other tube amps in this list. Huh you guessed it, tonal balances among mine get all over the place, measuring +/- 3 dB 50-20kHz on my amateur test bench. No amount of TFK ECC82/83 tube rolling can cure these, not even with new tubes from the New Sensor Group. I'd like to say it plays music with monosodium glutamate (MSG) like we see on "SOME" Chinese food. It compels you to fall in love immediately with whatever it is dressing, but the more you take it, the sicker you become with headache, swelling tongue, short breaths etc. Until you stop taking it. It has a special sibilance to its sound, not annoying but quite likeable in a way - the MSG I was referring to. And it has the most plethoric array of vinyl curve adjustment, and it even runs a good "loudness/controur" knob to tune the sound to your liking. But unlike the C11/C22 and the M7 T/C, its tone adjustments are non-stepped, meaning you cannot return to absolute flat every time you have moved them around. I'd like to think of the C20 as a special euphonizing spectacle that turns E. Taylor backwards 40 years in the beholder's eyes. If something plays even the slightest way of harsh thru it, that source is really BAD.)
7b. Heathkit WA-P2 (1955 mono design, most were kits built quality questionable. But if owered by modern rectifiers on DC heater 6.3V and 320V and LCRC with more generous capacitance, it is my preferred daily horse. Updatable on V3 from 12AUX/ECC82 to 6CG7/6FQ7 if PSU heater upped with 600mA more, to 1500mA or more. Sounds a bit like a McIntosh C-20, sweet tone and highs, good bass, and warmth overall, tho' details a bit lacking, background a bit more noisy and slightly less dynamic on line inputs. However, it gives very good vinyl curve support adjustable on the bass and the treble slopes to suit LP WES RIAA 78 45 etc. You may say, a cheap ticket to oooold oooolde vinyls and shellacs)
8. Yamaha C-2A, Nakamichi CA-5 II (similar sound style to CA-7, both well made on mostly discrete components, clean background, dynamic, but bass a bit lean on both less so on CA-7, otherwise superb as a daily run horse)
9. Heathkit SP-2 (If used on original Mullards EF86/12AU7/12AX7, it sounds better than WA-P2. Otherwise, still surprisingly good, but less warmth at mid-bass.)
10. McIntosh C-28 (My pristine used example didn't last my patience for 1 week. Then C11 back in. Funny, considering the MX113 with C26 preamp guts in, sounded better to me with rich tone and lovable texture. SIgh! C'est la vie. On ne sait pas pourquoi.)
11. Nikko Beta 20 (Close to Yammie C-2A performance with better bass "texture", read: not muddy. Mostly discrete components. Priced right, a good used work horse.)
Worst List
12. Hitachi (Lo-D) HCA-8500 (Thin and tinny mostly, but gracefully so and not grainy, but still enjoyable with vinyls thanks to its sweet phono stage)
13. NAD 1000 (What the thing is it about this? It didn't even last 1 hour on my test. Non-3-D, bass going shallow, though highs were slightly better.)
14. Nikko Beta 600 (The best on recording and EQ with Tape 1 and Tape 2 outputs individually switchable, and 2 processors' loops. Lit volume and tone knobs yell out 1980's style. I never like its all opamp circuitry, you know with the straight 8-pin ones. Which makes it not much worthy in terms of upgrading today. But for DJ, yes def'ly go for it.)
15. Dynaco PAS-X (What the fuss is all about it? I have 6 of these. None of them sound good enough to me. 2 dimensional, bad tone circuits, very bad PSU design. All of my examples give 9 VDC half-wave rect'd to its 12V heaters only!!!!! That is, even when I replaced the selenium rectumfrier with a silisone one. Gosh !!! Performance-wise, nothing good that I'd like frorm it. Not Hi-Fi to me at all. But as to Dependability and longevity, yea you bet.)
16. NAD 3020 Pre section (Sweet sound, but that's about it all. Good for background music, light Jazz and FM, say Andre Previn and Mancini the like)
17. NAD 1155 (Mine was the Proton-badged one. Good as a work horse, but HiFi, na......)
18. QUAD II (I returned my loaned example to my friend having declined to buy it cheaply from him. So much abt British sound to me then, until 15 years later when I got my Leak amps. The Quad II was blurred, nasal with voice ....... arghhhh .... Probably just that loaned example.)
19. NAD 1700 Tuner-Preamp (Initially I had liked it in my bedroom for its versatility, but when I moved it to my main system, it started to reveal shouty mids, insufficient bass, limited dynamics and worst of all, grainy trebles. It performs surprisingly well on AM extension and FM sensitivity, tho'. I guess it is the same as 1300 the preamp in its guts inside.)
Except the Quad and the NAD 1000, I still have them all now and I switch from one to another regularly, say twice a month, to enjoy them. I do mod them and maintain them to ensure their useability when called upon. Hahaha, yea I think I'm still fervently enjoying this hobby ever since the 80's.