@OP, try to remove the converter from the chain; Since 110V power supply is only in US, those companies who sell in several countries have transformers with extra tappings in the trafos. It makes sense for them to source trafos with multi tappings though they are a little more expensive as cost of inventory holding cost of trafos of different voltages is much more high.
I've read about this extra tapping in posts of one of our FMs who converted a Behringer active X-over working on 110V to 220V by just using the extra tap lying in the amp. I had a NAD pre-amp working on 110V which I sold to one of the FMs. I have also advised him on the conversion thing. He took he advise FM who did the modding job on the Behringer and could do the conversion easily. It would surely make a world of difference to the SQ. I'm not mentioning the names of FMs as I'm not sure if they would like their names to be revealed. PM me and I'll pass on the info after seeking their approval.