I wouldn't be against the TAS7 Its just the right rack(Sound anchors maybe), dedicated power and a known parts path in the future.Okay, there seems to be a confusion on this Krell amp naming.
"TAS" actually refers to the amp with the full name of "Theater Amplifier Standard". This amp was part of the Evolution series and was manufactured around 2002-2005. It was a 5 channel amp only.
When you say "TAS7", you might be referring to the newer amp which has the full name "Theater 7". It should NOT be called TAS7. This is a 7 channel version of the latest Chorus or XD series amp and has the same smooth / lush / colored sound.