Hi,
I made a comparison of the TC-50 to the Rectoverb 25 and put it on Soundcloud (don't have the link handy, it is somewhere here in this forum). The TC-50 Channel 2 is way thinner than the Recto or Mark V. I noticed this out of the box when I got it and it hasn't changed. I have to roll off my guitars' tone knobs when on the neck position. For me this is unusual, I tend to like the tone knob dimed on the neck pickup. No pedals, ohms set correctly. Channel 2 is thin. I usually have treble around 9-10 o'clock, mid at 1 o'clock and bass at 3 o'clock, gain about noon.
Note: Mesa recommends that the treble may have to be rolled off on channel 2 and 3 when playing with low gain settings. So, I think this is a design thing and what gives the TC-50 some extra bite or grittiness and emphasises some higher frequencies when compared with other Mesas. Just my opinion.
At any rate, rolling down the tone knob on the guitar really has a massive effect on the TC-50 channel 2.
Another thing I noticed (and just remembered)....when using my Wah pedal with channel 2 at a band practice (i.e., drum volume) it felt like the sound volume would just disappear when the pedal was cocked "just right". In other words, when TC-50 wasn't reproducing some frequencies as much (as evidenced by the much lower volume at some wah pedal angles). My thinking is that the Channel 2 really emphasizes certain frequencies and this makes it quite sensitive to tone knob and wah.
Mace