I am starting new clone with one 4780 per channel in parallel. I kinda have problems to find 22V RMS voltage output toroids here in Benelux. Conrad has only 18 and 30V for 400VA and 500VA toroids. for 100W RMS per channel, calculation shows 22V at 4 ohm. Should I go for 18V, 30V or something (somewhere) else?