I have found, with my MB-185's, that Albert is correct about upgrading the input tubes (NOS 60's Sylvania goldpins recommended by Upscale were better than anything of more recent vintage I had lying around the house). For power cords, I don't play in the same range that he does, but have found that a base model Shunyata cord substantially raises the get up and go factor vs. the stock cord or the other alternatives I've got, and it's possible their top amplifier cords would work even better.
Also, there's the issue of the coupling-capacitor upgrade to the InfiniCaps VTL uses for their Reference series, an available factory option that's said to sound more highly resovled yet more refined as well.
But all this aside, my experience definitely indicates that tetrode mode will yield the best extension, driver control, dynamic impact, spatial delineation, and transparency/resolution these amps are capable of, although at a slight cost in terms of natural tonal balance (a bit leaner below, a bit brighter above) and ultimate harmonic purity vs. the triode mode. So while you might prefer triode for intimate vocals, I'd try tetrode again for larger-scale stuff.
Also, there's the issue of the coupling-capacitor upgrade to the InfiniCaps VTL uses for their Reference series, an available factory option that's said to sound more highly resovled yet more refined as well.
But all this aside, my experience definitely indicates that tetrode mode will yield the best extension, driver control, dynamic impact, spatial delineation, and transparency/resolution these amps are capable of, although at a slight cost in terms of natural tonal balance (a bit leaner below, a bit brighter above) and ultimate harmonic purity vs. the triode mode. So while you might prefer triode for intimate vocals, I'd try tetrode again for larger-scale stuff.