Building an all analog system around Magnepan .7 for 4K and under

Rega & Marantz make such products.  You'll want good current delivery to power the Maggies.  Beyond that, you'll need to do listening tests.  IIRC, Music Direct will allow returns for 60 days or so as will Audio Advisor.

I have heard Maggies (3.7i and 1.7) on a $4,000 Rogue amp and it sounded very nice.

Dunno re the Sphinx but be sure it can deliver a lot of current at 4 ohms.

Is there any chance I can convince you to put the turntable in another room to acoustically isolate it from SPL in the listening room??  That will solve a host of problems....

setting up the table in another room should sound better as it will greatly reduce acoustic feedback to the table, arm and cartridge

not to rain on your integrated parade too much, but it will also be best to put  a separate pre-pre amp for the cartridge in that room too

the reason is you generally want to make the longest cable runs the one least likely to interference & signal degradation - that means short cables from cartridge to pre-amp, and from power amp to speakers

the ultimate would be an all digital feed directly to the base of the drivers with D to A conversion done there -- for an all analog system you want to emulate that (all other things being equal)

I am not aware of anything made this way but a quality pre-amp with a remote control head would be ideal - you'd want not just an IR sensor for the remote but also the readouts on the remote head and then the entire pre-amp would go in the closest or other room with the turntable

It sounds like you have not yet bought speakers....
Magneplanar may still have their loaner (return) program going for the 1.7i speakers.  A classical musician and jazz drummer combo sounds like you must live in a fairly large city, so your Maggie dealer should set this up for you.  Dunno if they do it for 0.7's, but there is no such program for the 3.7's (I wanted to try those to replace my 1.5QRs).

BTW, a larger physical speaker does not mean the speaker is also larger in an acoustical sense.  I called Magneplanar and Mr. Maggie (Wendell) told me the 3.7i speakers were acoustically smaller than the 1.7i.  You should call them up and talk to Wendell about exactly which speaker would be best.

Maggies are perfect for your source material.  They want you to use the DWMs and not dynamic subs (many do this, but they are difficult to integrate with panels).  The DWMs can be made to look like coffee tables but need ot be at the same distance from your ear as the other panels.

I see this thread going into room treatments... so you may as well post a photo of your room in the section for that...