Compare: Modwright LS 36.5 & Audio Research LS26

As a former owner of LS-26 I can tell you that its not typical tube sound either. Its quiet close to SS IME & IMO and paired with the wrong amp can be quiet lean and unforgiving.

I've compared the 36.5 with the separate PSU to a BAT 51se and a few months later to the 52se. The Modwright was, in my system and to my ears, better in several ways - cleaner, stronger transients, deeper SS with more air and separation. Everything was just a bit more palpable, more there. SS width was similar. All are very quiet. I could live with the 52se, it's great but I like the dynamic transients of the Modwright more. Notes jump, drums sticks THWack (while deep in the SS a brush still sounds like a brush.) Vocals were similar but the Modwright produced the fine details while the 51se was more polite. The 52se really did vocals right but the Modwright had them a touch more forward, which I like, mostly.

I haven't heard an ARC pre in my system yet. I have heard the Ref3 many times at shows and I like it but... If I were to place the sound of these three or four preamps on a scale from tubey to SSey I would say the Modwright sits right there between the 52se and the Ref3 - the Ref3 is not very tubey to my ears, the 52se a bit more. However, with certain fancy NOS rectifiers the 36.5 moves more towards tubey (RCA 5U4G, for example) . I don't think it will ever be considered warm though. Full? Sure. Meaty, sure again. But never syrupy.
The 36.5+ strikes the best balance that I have heard in my system yet between SS like guts - bass and dynamics, the air and shimmer of tubes and the BIG, DEEP soundstage tubes produce when done right.

I just reread your system and I will add that which ever pre you choose, Ref3 or 36.5, you are going to have one fantastic system there. I might venture to say too that your choice might rest more on your TT and cart choice than anything else.

What's your vinyl set up?

Copilot:
Thanks for your thorough and thoughtful analysis.
My analog front end is a TW Acustic Raven One Table, a Graham Phanton arm and a Dynavector XX2MkII cartridge. The phono pre is a Modwright SWP 9 with
NOS Mullard 5AR4 in the power supply and old Russian military 6np1's in the gain stage.
The tube changes have made the pre a bit "tubier" while preserving the resolution and staging of the stock preamplifier. Cabling is Synergistic research Tesla Accelerator.
The line stage upgrade is the final major piece...other than power cords etc.
Your input is valuable.....much appreciated.

Wow. Perfect. It's going to be even more better than I thought.
I love the TW Acustic Tables. I spent most of my time at RMAF this fall in the two rooms hosted by Jeffrey and Thomas. I plan on buying a Raven table in the next 6 months - must save some money first. Patience!

Would you agree your set up leans towards more accuracy than romance now? Do you plan on changing up your cart?

My opinion is the ARC preamps may be a bit too lean in your set up - unless you like extremely tight, really crisp sound with the sort of brilliant tonality the Ref3 is known for. I tend towards liking that myself but I have always found the Ref3 one step too far. I have heard the Sophias with ARC amps and the Ref3 several times now. The sound has been great for a portion of the time but for an equal amount of the time I found myself pushed by the lean, almost etched sound. I honestly can't say what was going on - bad recordings, wrong load - I can't remember if it was the TT or the digital that was giving me a headache but it's happened a few times.(I really like the Sophias with BAT tube amps. They add just a bit of romance to the Sophias - which seem to me to sound dry and sterile if not matched up with the right amps.)

Seeing you have already swapped rectifiers in your SWP I imagine you like a bit less of that and more heft, more bloom. The 36.5 has a bit of that but not much. It is a 6h30 pre after all - it's very neutral. Swapping out the rectifier in the 36.5 will do the same as it's done in your SWP so you know what's possible there.

Is the same thing possible with the REF3? I don't know. It'd be good to find out.