Step Up Transformer 100v

The EHU600 is limited to 600W. Find the maximum draw of what you want to plug into that and double it. 600W is small for an amp. unless it's a flea watt.

I think BigShutterBug is referring to these:

http://www.geocities.ws/jonrisch/catch2.htm

http://www.signaltransformer.com/content/power-supply-step-updown-power-isolation-transformer

And this is an enclosure that can fit up to the 2KVA model.
http://www.hammondmfg.com/dwg14d.htm

Max power consumption for that Naim is rated as 350W but, being class B, it'll want that faster than you can say ,"Now!", to recharge capacitors.

Bigger transformers have a lower impedance, thus less likely to create distortion at higher draw. The downside is that bigger transformers will have a higher "idle" current and will cost you to run.

At 16 Kg for the 2000W Swallow, that looks more like a "converter" or autotransformer, which offers no isolation and noise reduction. They are quite efficient and do the job.