Avalon VT-737sp Class A Mono Tube Channel Strip Limited Edition Circuit topology Four dual triode vacuum tubes (Sovtek 6922), high-voltage discrete Class A Gain Range Microphone: Transformer balanced 850/2500 ohm, 0dB to +58dB Instrument: Maximum input level and connector types Microphone26dB@25Hz, +30dB@1kHz balanced XLR Line +36dB balanced XLR Maximum output level +30dB balanced 600 ohms, DC coupled, discrete Class A Instrument+30dB unbalanced front panel jack socket