Best Full-Function Preamplifier

You gotsta pay for top echelon sound.   I would listen to a number of different preamps and a bunch of external phone stages along with....   

I owned a Zesto Leto preamp.  It was great , their latest Ultra II is even better.  But what they really specialize in are phono stages.  

Audio Research, also makes great gear ...  Pass,   many others.  

I would want separate components in every situation,  in every price range...a great phono stage is almost NEVER included in state of the art preamps... maybe a very good one, but not a reference one 

McIntosh C2700 or one of the other many they have, make sure it has the DAC2 board and your good to go. excellent DAC with multiple in-outs for digital, ARC for TV integration, the C2700 is a Tube preamp with dual phono stages MM and MC, then there is many RCA and balanced in and outs. Tone controls if you need them, switchable of course. so many features i don't know of another preamp that can match it for features. 

There is only one preamp with built-in phono that I would consider, Atma-Sphere MP-1, in the no compromise category you’re looking for.  I was on the phone with the owner, Ralph Karsten, just last week, he normally picks up, trouble shooting some tubes.  You’d be hard pressed to find a better company, products or person to deal with.  I own two of their components and about to buy a third.  Highly recommended.  

Its getting a bit old, but it is still in production and a great sounding Preamp...

SST Ambrosia 2000..... Is full function... True Balanced, single ended, world class phono and headphone stage, tone controls to boot. Yes, I’ve sat in front of it many times, it competes with the best. May not be your cup of tea, but anyone who has spent real time with it will tell you that its quality. 

It sounds like you are talking about the Classe Delta PRE.  It sounds amazing and has the perfect complement of features including a great phono stage.  I love mine and I threw the HDMI card in there to get ARC from my TV.  No complaints.  I’ve also had the Hattor passive line stage with tube buffer, the flagship Parasound, and the list goes on.  It’s no MSB, for example but what is?