[Taycan]

Yes, I can imagine that matched tubes can be difficult to find.
After nearly 30 years of use, I recently looked into replacement of the tubes in my SRM T-1, and discovered that the existing tubes that came with the unit still out performed anything I could find/test.

 

[padam]

Just fired up the SRM-T1S after many months. Performs admirably, especially with no warm-up.
Sound seems concentrated in the middle of the frequency range, forming a narrower spherical stage instead of a big rectangular shape that I'm used to, resulting in a much more forward presentation than the Carbon, which is more laid-back (as long as the paired headphone has no issues...) so I am listening at a slightly reduced volume.
Still unmistakably Omega of course, not intimate like a Lambda, just not as grandiose.
Biggest trade-off is the murky bass, does not reach nearly as low, so quite a bit brighter and the flat dynamics make it a bit rough and ready in comparison.
A more ideal match would be somewhere in between the two amps, e.g. having the full-bodied low-end, but still with a bit of thickening on the midrange.

 

[Taycan]

Very interesting observations...thanks.
I was listening to some dummy head binaural choral music, and orchestral music that a friend recorded recently.
i tend to agree with your perceptions...for me the Omega/SRM-T1 combo offer a super detailed, clean midrange, but are somewhat thin in the base. I also find that on many recordings, the violins get a bit tizzy, and femaie massed voices can get a bit screechy although it could be the recordings that are too bright.
I love the way the Omegas recover the hall acoustic.