To me, you just can't look at the impact of one component in the chain. If the system is not, overall, accurate and revealing, changes are masked by the other components in the change. I have, other than Touch/DAC, an all tube system. My experience with digital attenuation is far from favorable. IMO digital attenuation makes every thing sound like it is running through a CD player's cheap attenuation stage. Even with the Touch, digitally attenuating the output to the DAC makes the music flat, suffer a loss of timbre and adds grain. Will the technology "get there"? Maybe or maybe it already has. I am just not a player in higher $$$$ digi.
But bear in mind, I am NOT a big digi-fan. I stream to a Touch out to an NOS DAC. The music, to me, sounds better than a CD player, but generally digi-music is for background listening. Serious listening is vinyl or R2R. So take my comments with a HUGE grain of salt.
Cheers,
Geary