Macintosh C22 MKV

I have the M 700s. I’ve been wondering how the M 1200 sound with the tube input stage. I take it, it doesn’t match a full tube amp. 

No, not like a full tube amp. They do add some "air" to the sound.

I have the McIntosh C2300, which is also using 6 12ax7 tubes and is very similar to you C22...  Depending on which phono you are using (MC or MM), you only need to upgrade 4 of them.  2 for the left & right phono (ie. I use MC), and 2 for the line level (all the music goes through the line level).  For all 4 of them, I am using West German vintage Telefunken smooth plate tubes.  I think they sound great in this preamp.  Very smooth and musical. 

Thanks, I'll look into the Telefunkens.

I have the C22 MKIV.  I do not use the MC or MM phono stages.  In the two line stage slots I use the new JJ ECC83 "MG" (which stands for Mid Gain).  

These are by far the warmest, most classic tube sounding tube I have ever used.  Maybe too much but they at $19 a piece not too much to lose.  

Sound is super smooth- no sibilance or glare.  Big bass.  No burn-in needed.  I have used tubes for years and these are the only ones that have that classic tube sound.  NOS Mullards or RCAs not even close.