Artmaltman,
If the stock Sovtech 12AX7 is found wanting, you can always roll another one in. One could always question whether a two tube circuited preamp is providing identical signal handling capabilities without a matched set - and even then ...
The review in HI-FI+ gave it a thumbs up on channel separation, but in the end you're right - we are talking about a $160 (street) phono stage. But for those whose systems don't provide tape outs and headphone jacks, I think this little puppy is worth a look.