Well there’s a great deal that you can do to an amplifier to change its voicing, gain, dynamic responsiveness etc.. And at least 80% of those modifications don’t require an additional dual triode (2 more amplification stages) requiring grid load + plate load resistors + cathode bypass capacitors & resistors + coupling capacitors to connect with the rest of the preamp and to each new triode with one another. Lead dress, routing the new wiring to the new tube socket’s pins connecting to the new components has to be done right or it’s all squealing screeching & hum. which need to be carefully selected so that the tubes’ voltages are biased to proper operating conditions, As well as contributing to bass response eq voicing and gain levels. Oh and even done right adding 2 more gain stages to an already hot preamp means increasing noise by 2x.
Now remember it’s a dual triode, So the component’s carefully selected & tweaked to get the right voltages and voicing all must be done.. TWICE! I honestly have way oversimplified this and left out far far more than I’ve mentioned.
**Ive said all this not to make myself look smart or to overwhelm & discourage you
@griff10672 from getting your hands in the chassis and getting your amp sounding like you dream about. I do it to caution you about the many potential pitfalls and (more than likely) turning your amp into a bench ornament. Because I tore my hair out exasperated as I routinely murdered perfectly good amps and built a junk museum of mod attempts, badly or never-working scratch build heads and assembled kit builds. Which eventually lead to becoming proficient with audio equipment electronics and I’m sure you’ll get there if that’s what you want. But I don’t want that frustrating wasteful path for you, and wish an experienced forum member (this is my first day on here) had done so for me..