The Vt-737sp and the AD2022/M5 are very different microphone preamps. The Vt-737sp uses vacuum tubes while the AD2022/M5 incorporates 100% discrete transistor based solid state electronics (no vacuum tubes). The AD2022 and M5 employ the same basic amplifier topologies. However the AD2022 has a fully balanced output and variable input impedance selection for changing the sound of microphones. All three of the microphone preamps run in Pure Class A mode and use discrete electronics for amplification. Tube preamplifiers, offer a very different sound in comparison to a solid state preamplifiers.
Avalon's designer Wyn Morro believes that tubes achieve a very unique and wonderful sound. However, for 100% pure sound, the design must be solid state (Avalon's unique design). The AD2022/M5 is a higher quality microphone preamplifier than the Vt-737sp. The AD2022M5 has more detailed highs, better low-end definition, and is much quieter.
The sonic differences between the Vt-737sp and the AD2022/M5 can be compared to a spotlight (Vt-737sp) and a flood light (AD2022/M5). The Vt-737sp has a "close-up" round sound while the AD2022 is very detailed and open capturing more of the subtle sub-harmonics and reflections in the room. Now, all of the Vt-737sp owners might be thinking that they may have bought the wrong preamp. On the contrary, the Vt-737sp is a fabulous unit. It was the first and still is the best "Direct Recording Channel" or "Channel Strip" on the market for any price - bar none.
The Vt-737sp was specifically designed as a tube preamp and has the unique sound that only tubes can deliver. The Vt-737sp has the most clarity, transparency, power, control of any tube preamp available. It is a Swiss army pocket knife for recording. The Vt-737sp has the necessary, high performance, functions built-in to handle real-world recording demands: preamp, compressor and parametric equalizer.
Should you trade in your Vt-737sp for an AD2022/M5? No, but you might need both preamps in your arsenal. Try both preamps and experience for yourself the difference in the sound.
Below is a table comparing the Vt-737sp and AD2022/M5