Apogee Scintillas will sound like anything you care to listen to. I like it to do all. I have heard it with Pass Labs amps of my own, and the newest too. With class A amps, the Scintilla sounds bloated in the bass, the mids receded, and the highs rolled off. Still, it's cardioid sound radiation is magical.
Now, with the trice improved H2O monos and the H2O Fire preamp, my speakers have the ability to sound like anything it is shaped by. They have sounded bold and husky like a top drawer class AB amp, dreamy like tubes galore, or cracking crazy real.
The source is paramount. It must be a non oversampling DAC with no filter and super fast diodes. There can be no substitute. After that, only the cables are left. On this system, the cables will make or break the sound. I found absolutely no commercial cable gave me what I wanted. The Shunyata Helical was very good on attack, strong highs and lows, but the mids were thin. Anti-Cables provided a marvelously romantic mid but with no excitement, and rolled off highs.
On a whim, I ordered some all nines copper ribbon and covered the ribbon with Saran Wrap. Because the negative charge travels on aluminum ribbon down the five feet of the speaker, I figured it would do no harm to run aluminum the rest of the way. I was right.
The first time I pushed the transport, I was knocked on the floor by the first stanza.
My cables are now sandwiched between tape of awesome specs. The truth about class D is it is wholly misunderstood. It has some really serious requirements for fulfillment.
Now, I can listen to any venue of music and get the full artist's intention. Classical music rises mightily and ebbs to quiet solitude with ease. Women singers step forward, with no false warmth, just the beauty of their voices. guitar and piano is freaking real.
I don't know if this recipe will work with all class D amps, but I do think it will bring out the best of any ICE amp.
This is a great owner's review of the Fire preamp:
http://www.audioasylum.com/forums/amp/messages/13/136780.html