Airtight 300b or Coincident 300b?


I have the chance to buy either one, 2nd hand used for almost the same price.  Any recommendation which one i should go for?  On the one hand, one is a monoblock while the other is a well established brand using high quality tamura transformer..  Any advice is appreciated.

I am using a diy audio note m7 tube amp driving a pair of audio note an-e spe HE speakers.  currently using a pair of yamamoto a08s.  I have used audio note kit 1 300b before so these 2 would be my benchmarks.

i listen to classical music, mostly chamber, operas, symphonies.
chaccone
Which Coincident 300B amp are you comparing?  The current Frankenstein or the older MP300B?  I have listened to the Airtight ATM300B and both Coincident 300B amps with Avantgarde Duo speakers and my preference was for the Airtight.  Very quiet amps with a lot of detail and dynamics.  Very well made also. 
The current Frankenstein.  Thanks for sharing.  for your audition, were both of the amps using the same 300b tube ?