The solid state Ayre K-1xe, (which I own and use), has a near reference quality phono stage. The heat output seems to be near nil, (I've never noticed it being even warm), however, I will state that this unit does have a separate small power supply box, in addition to the main unit itself. (I bring that up as you stated you are pressed for space.) Used this runs around $4-5K, (and that is the only way it is available, as it is out of production).
Other preamps that I have researched and think would be slightly better, (and more expensive of course), would be the tubed Atma-sphere MP-1, Mk. 3.1, and the solid state Halcro DM-10. Both are reputed to have reference quality phono stages. However, both are also on the large side, as the MP-1 is a dual box preamp, and the DM-10 is taller than most, (all?), of the preamps I know of. Used these run around $7-8K, and new it is about double that.
Note: All three of these preamps can accomodate, (and prefer), a balanced input from the cartridge. (FYI, I use the balanced input on my Ayre as well.)
Good luck in your search!
Other preamps that I have researched and think would be slightly better, (and more expensive of course), would be the tubed Atma-sphere MP-1, Mk. 3.1, and the solid state Halcro DM-10. Both are reputed to have reference quality phono stages. However, both are also on the large side, as the MP-1 is a dual box preamp, and the DM-10 is taller than most, (all?), of the preamps I know of. Used these run around $7-8K, and new it is about double that.
Note: All three of these preamps can accomodate, (and prefer), a balanced input from the cartridge. (FYI, I use the balanced input on my Ayre as well.)
Good luck in your search!