I have moved on to my 17 year old, unused EAR 864 paired with the EAR 890. I used Stillpoint Ultra SS under it. I replaced the line tubes with a NOS Mullard CV4004 for a wide frequency response, neutral but full bodied mids and wide dynamic range coupled with a cleartop RCA 12AU7. The phono stage has a D getter old Sylvania 12AX7 in front and double silicone rings on the rear two stock 12AX7s (JJ or Ei?). The line stage sound now has tremendous dynamics, extracts subtle musical cues, deep and wide soundstage and very wide frequency response (no lack of very deep, punchy bass here). Is it possible that it has a better line stage than the EAR 912? As Atkinson reported, he was concerned with the limited overload capabilities of the 912. It only has a stock fuse in it as does the EAR 890. Tried Synergistic Research blue fuses but the difference was too subtle (unlike their power outlets-huge improvements). Strange that those same type fuses made a remarkably huge difference on my large custom monoblocks.
As to the phono section, it sounds very good as is with a Dynavector 20X2L plugged into it versus using another set of phono cables with a Zesto Allesso SUT. It sounds more dynamic directly into the pre-amp which I suppose has inferior transformers to the Zesto but appears to be a perfect impedance match like the Allesso (at 100 ohms/max output).
I have also moved on for a year from the COS Engineering D1v. I found it lacked the body of music and foreshortened depth with my previous gear. Also, one neighbor in a $500K system was using Pangea power cables at the time. He replaced them with 6 GroverHuffman power cables and made a huge difference. I replaced the COS with an extremely modified Benchmark HDR1 (new filter caps, tantalum, power caps, new audio board, $50 audio grade regulators replacing 50 cent computer grade) Arcam Delta 270 CD player and Delta 250 transport with 15+ high quality audio filter, power and bypass capacitors as CD transport. The COS went back in now and has all the warmth and depth it was missing into the EAR system.
So, the sound I am receiving now is high end as indicated by visitors who have 50 years experience in high end audio (retailers and manufacturers). The speaker limitation is mostly in limited seating (imaging best in center seat only), larger ambiance (pending a quadradic diffuser), resolution (although I am hearing the subtlest details and dynamic shading as I've only heard in really expensive systems). The tonality is spot on. Dynamics are superwide. Bass from 6-12" woofers could have more texture but are super deep, comparable to subs.
Two friends and three local retailers told me to try the EAR 912 as it has fabulous sounding phono stage. The last time I heard it, it was tubed with NOS Amperex or Philips 6922 tubes. I read now that ECC88 (6DJ8) Telefunkens sound superior to the PCC88 (7DJ8). Really? I only know the Tele 12AX7s which I prefer not to have in my equipment.
I suppose I will try the 912. It is possible that the 912 limited overload situation doesn't exist on the 864 and/or that the line stage is better on the latter. I intend to upgrade my speakers early next year (hearing Aequo Audio Adamantis and possibly Marten Bird 2 or Parker Quintet 2, can't afford the best, Von Schweikert Ultra 7).
