Pretty nice unit... I was building a very similar version at the same time : )
Have a look at the pic!
I am using the same Gain-Control. Two Grayhill rotary switches for the input resistor-pairs and the feedback resistors and also brought the +/- 1,5 dB Trim-Pot to the front. I am not using an additional PAD as the Gain-Range is from 0dB up to 63dB (for sure, you Gain-Range is from -20dB upwards.
I added a bridged T-Pad Attenuator for the Output (also a Grayhill). So, you are able to drive the V672-transformers into nice saturation. Together with the "free-Mode" of the Gain-Control, you have multiple possibilities to shape the Sound.
I also brought the V672-internal Highcut (Air-band, 15kHz) to the front and added a DI-Input plus link. So, you are able to connect your Amp AND record the signal. The LED-Meter is a Neumann MO33 which they are using in their U5072 danner-format meters. The brightness of the LEDs is dimmable.
I am thinking about creating a 2-channel bridged T-Pad, so, that I can also use the second transformer-balanced output as well.
But that means a Grayhill-switch with crazy 38 Resistors on it!
It is very nice to see all these DIY and racking-projects and all the crazy people who are spending so much time on it! Very inspiring, thank you all!