Thanks for your input guys. I have what's probably a bottom-of-the-barrel energizer, a good condition but very old SRM-1 MK2. Soundstage and details are decent, but dynamics and bass just suck. I've recently acquired a very powerful speaker amp, it's actually a 5.1 channel A/V receiver with a great headphone amp too, Kenwood VR-406 putting out 500W; 100W per channel. I'm looking for much improved dynamics and maybe bass, or I could boost by EQ - so would you still recommend the SRD-7 transformer?
The owner of Mjolnir doesn't seem to be able to get any Lundahl transformers now, probably why he didn't answer when asking him twice about any differences in sound. Is there any Lundahl energisers I can find from another company?
You can build your own energizer if you have a little bit of experience in soldering. Energizers are extremely simple: An Input protection circuit + transformers for channels + transformer for bias. That's all. http://www.audiodesignguide.com/my/stax_transf.html you can check the circuitry here. What Birgir claims is that he custom ordered his own lundahl transformers which are perfectly designed for driving electrostatic headphones. The winding rate of birgir's transformers is 1:17, That's all I know. If you don't aim for absolute perfection, you can just pick required transformers recommended in the circuitry schema.