AFAIK there isn't a published biasing process for the SRM-007, however the biasing for the T1/006 series is similar, see thread here:
https://www.head-fi.org/threads/tube-change-biasing-a-stax-006t-ii.415385/
IIRC, TVR1 adjusts the voltages between the + and - outputs for each channel, and the voltage probes should be inserted between the + and - outputs of either channel and adjusted to close to zero as possible.
TVR2 adjusts the voltages of the outputs to be close to zero volts with respect to ground - one voltage probe should be inserted into either th + or - output of a channel, and the other voltage probe should be connected to chassis ground.
The 007 has two additional adjustment pots, TVR3 and TVR4 - they adjust the plate voltages for the two sections of each 6CG7/6FQ7 to be equal to each other. Connect a voltmeter between both TP1 points or both TP2 points and adjust TVR3 and TVR4 so that the voltage between the two is zero.
There will be some thermal drift as the amp warms up, and there will also be some change between the voltage with the cover on and the cover off. For the T1, Stax specifies within +/-15 volts of zero as acceptable.