No idea on the gz32. Have not heard. You see, this is why I hesitate to whole-heatedly recommend WA5. Unless you get it used at a great price. It's not a tube rollers dream. It's a tube rollers nightmare. And even then, you have to figure out if the boutique cap and parts updates are worth it too.

Rectifier will affect bass slam, tightness, etc. on the WA5. The WA5 without the big 274B (sophia or EML) have sounded bass lite, lacking dynamics, or wooley. That's the foundation. Your power supply.

The 6SN7 driver tubes tend to sound more alike than not, with some high-dollar unobtainable overpriced exceptions. 300B tubes are all over the place in terms of sound. So because of that, the 300B will affect the rest of the sound most. EH 300Bs are very underrated, cheap, and have a typical 300B bloomish sound. You may already have something better or different. Sylvania GTA/GTB 6SN7 is a good place to start - plentiful and cheap.

When swapping rectifier tubes for unregulated PSU's it's not the rectifier that changes the sound, but rather the change of operating points of the whole amp. Can't say if I approve of such designs.

Part of it is also due to the dynamic response of the diode. In a single-ended design, current draw from the power supply is proportional to the signal. Unless the power supply is shunt regulated, this means that the diode is in the output current loop. As the triode swings, it draws varying amounts of current which is pulled from the power supply.

The datasheet for the GZ32 shows the diode I/V curves for choke and capacitor input power supplies. In capacitor input supplies, the curves aren't purely ohmic- their impedance is load-dependant, and probably plays a part in why different rectifier diodes sound different.

Recovery characteristics probably differ a fair bit too, between different diodes, but I don't know enough to say how exactly.

I am currently running the mullard gz32/cv 593.  It was available for cheap so I thought I grab it as a quick upgrade.  How is that tube compare to the 274b mesh?  Are you referring to the 274bmesh Sophia or something else?  Of the three type of tube in WA5 do you know which one affect the sound the most.  I probably going to try to get that tube to sound as much to what I like then.  Thank you for your time Purrin.

I think the rectifier and 300B improves the WA5 the most, but the driver choices are significant to system matching esp for brighter headphones such as the HD800 unmodded.

My favourite combination for the WA5 was GEC U52 (rectifier), AVVT AV32B (power) and Syvania 6SN7w metal base (more resolution, soundstage and speed) / Tungsol BGRP (fuller body, more intimate, better bass).

I'd appreciate you opinion too Marv since I will have planers and the HD-800 soon.