I just posted the following on my iCAN review thread:
The Sony MA900s continue to surprise me. I hadn't used my TDS202 sound enhancer in a while, and my instinct was that it would not work well with the Sony's as they are already so spacious and open with the iCAN amp.
But no harm in trying, so I pulled it out and hooked it up between the Tera and the iCAN. The TDS202 is a strange little device that boosts low level sounds in the mix and thereby brings out the details in the music. It also has the effect of expanding the soundstage. So it is similar to the 3D on the iCAN.
And at first it maybe seemed like too much of a good thing, but after a bit of mental adjustment there was a growing sense of wonder at the effect with the Sony's. First of all, there is an abundance of details and resolution. As Highflight described it when he bought the TDS on my recommendation, it is like removing cotton from your ears. But the surprising thing is how it also seems to fill in the body of the sound from top to bottom. Everything sounds fuller and richer, even the bass. I do not remember this happening with any of my other headphones when I have used the TDS202 in the past. Maybe it is in part because I am using the xbass on the high level of boost with the Sony's also. But there is definitely a fullness to the bass and mids with the TDS in the chain. In the past, it seemed to tilt things more towards the higher frequencies.
And then there is the spacious almost hallucinogenic soundstage with the Sonys and the 3D on the iCAN and the TDS202 all working together to create an amazing sense of wide open sound and almost supernatural instrument separation. This is the thing that my brain has to adjust to, but as I get used to it, it is quite addictive. The Sony's do this well by themselves, but add in the other two effects and it moves into another realm of spaciousness. And as always, if on a particular song, it really is too much, I can just flick a switch on the iCAN and bring things back down to earth. In fact with the TDS in the chain, I find I also enjoy the lower "one dot" setting on the iCAN which is a more typical crossfeed. Without the TDS, the sound can tend to flatten out a bit and be a little lifeless with this setting on the iCAN. But with the TDS, I can enjoy the benefits of the crossfeed filling in the middle and tightening up the soundstage without losing the aliveness and even an overall remaining sense of open spaciousness and still very good instrument separation. On some music, it is just what is needed. But most of the time, I just go into hyperdrive and fly through the vast reaches of interstellar sound with everything maxxed out for space and more space.