I retubed my VTL 2.5 with NOS Mullards but mine uses 12AU7 and 12AT7 types, 2 of each. I bought mine new in 2005. You may have an earlier version that used 12AX7s. The sound quality improved noticably. The tonal characteristics became richer,sweeter and more realistic without any loss in detail or resolution. It cost me about $140 for all 4 tubes and would recommend it. I may try Telefunkens alone and in combo with the Mullards just to experiment. It's fun but you need to let them break in awhile to get the true sound.
