Tube Amps With Good Bass Qualities

Another vote for Atman-Sphere.  I have the M-60s with the upgraded power supply driving speakers that are basically 10 Ohms (minimum is about 8, I think), and the bass is deep and articulate.   I couldn't be happier.  But as has been well articulated above, you have to have a happy match between speaker and amp.   If you don't get this right you are going to have issues.  BTW, these amps are gems from top to bottom.  Get the right tube complement and these amps sing like angels.

@luisma31, I've stuck with the SED winged C power tubes.  I haven't seen anything likely to be better for any kind of reasonable cost.  I've done a good bit of tube rolling on the 6SN7s, using a few NOS RCA, Sylvania, and GE tubes, as well as a few different current production brands.  Right now, I have a Shuguang WE+ at the position requiring the GTA/GTB tube.  I've tried other tubes in that position, including various NOS RCAs, Sylvanias, and a GE GTA, and I like the Shuguang WE + best.  It is a very large tube, and it will only fit in the isolated front position because of its size.   In the rear positions not requiring a GTA/GTB tube, the best I've found in the rear middle is a NOS Sylvania Bad Boy.  Every other tube I have tried in that position results in decreased dynamics and top end sparkle.  For the rear row right and left tubes, I really liked the early 50's NOS RCA grey glass.  I recently picked up one of the new Sophia Blue Glass tubes and rolled that into the rear right position.  I really like that tube, and I am thinking about getting another pair for the left rear position.  Those are very nice tubes!  Sweet and smooth.  I don't know how the various tube locations in the M-60s (MK 3.3) correspond to the MA-1 amps.   I'm curious about your experience with the 6SN7s.