Anovak, Did you in any way modify the circuit, when you changed from 12AX7 to 12AT7? Besides affording less gain, the 12AT7 is a very different animal from a 12AX7 in terms of optimal operating parameters. The 12AT7 sounds best with much more current, compared to 12AX7. The good news is that if you've done nothing to the circuit (and if you can live with the reduced gain), you can get better performance from your Jolida by changing a few resistors.
