What's he playing through?, He may want to consider adjusting the EQ on the 740. Also if he's using a MONO amp the sound quality should be compromised a bit. The 740 is a good sounding board. Again I would think some basic EQ changes may help there.

Squeak
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GEAR: Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller). SOFTWARE: Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.