Integrated for bi-amping with AtmaSphere MA1s


My speakers (Ascendo ZF3s) have separate terminales for each driver.  I am currently using Atmasphere MA1s for the mids and tweets, and using a Pass X1 and Aleph3 for the woofers.  I'm also using a set of old Entec LF20 subwoofers crossed over with a Behringer Ultracurve pro for the really low frequencies.  I would like to replace the X1 and Aleph3 with a more powerful integrated, and am not sure what to use.  I've been away from this hobby for a number of years, but my first instinct when I think low frequencies is Krell.  The S300i looks intriguing, but I've read that it comes from a dark time in Krell's history, and may not be terribly reliable, and not up to the stnadards of low-frequency reproduction Krell is known for. 
Is this a good choice?  What else should I consider?
honest1

Showing 2 responses by blisshifi

Using the MA-1 for the whole thing will likely not give enough bass output as the speakers have a nominal impedance of 5 ohm. One way to make it work well is to get a set of Paul Speltz’s (anticables) Autoformers ans only hook them up to the bass terminals.


While I found that using autoformers on the full frequency spectrum on my previous 4 ohm speakers (Legacy Focus SE) narrowed the soundstage, decay, and air, I tried using the Autoformers just before the speaker cable one for the woofer section and voila - bass was full, tight, and realistic, while the mids and treble were powered directly by the MA-1 with no Autoformers. I highly suggest this route, and if you don’t have Autoformers to try out, they’re not anywhere as pricey as buying a new amp.
@honest1 have you tried tube rolling the 6SN7s in the MA-1? I was able to get the near perfect sound signature that I wanted by mixing different tubes, two of which Shuguang black treasures, those two especially emphasized the bass and took away any harshness from the highs.