Hi All,
2sb737s are more recent. Also 2sa970.
I have had very good performance from Zetex ZTX550, 750. The Zetex parts are a small package, large geometry, 1A collector, made for switching, but the 1/f & other noise is very low. The transistor matching is for DC shift while turning the gain pot, as pointed out, but also to maintain equal currents & voltages in the different legs of the circuit.
The more equal everything is, the less problems you will have.
The Trans Amp LZ implementation has a DC shift trim, but it is dependent on speed of gain pot rotation & temperature drift. Turn faster, more thump.
I have used these gain blocks as dual (stereo) phono preamps with passive EQ networks. The Trans Amps are flat gain make-up only. They sound unbelieveable.
Best to All