I just got an EH Nano Small Stone & I love it!
To be completetly honest, it does lose a tiny amount of overall volume, but the full frequency spectrum is preserved. Granted, a phaser is dynamically sweeping the spectrum, so at some point all frequencies are quiter, however the low end extension is retained and the balance is natural. I put my handy $30 LPB-1 booster after the Small Stone & just a couple of db's brought the level up to where I need it in order to preserve the dynamic/loudness range I'm so anal about!
This is a great, small, easy to operate pedal with very warm tone. I wish it didn't require help with the volume (an onboard level booster would be such a great feature), but overall it's a killer little unit.
BTW, I got a great deal at The Perfect Bass & it was at my door in 36 hours w/ standard shipping!