Other than the OTL as above, the absolute best sound-matching I got was with an outrageously expensive Symphonic Line "Kraft 250 class A". This combo managed to "equalise" the low-bass output with the highs (i.e. bring the <100Hz in line with the 3kHz and the ~10kHz "bumps" that irked me).
It also made the top end more perceptible than with the OTLs (the small Tenors).
It also made the top end more perceptible than with the OTLs (the small Tenors).