I ordered the Rothwell MCL step up transformer from their web site and they shipped it direct from England, which was easy enough. I like it and would recommend it, though I've not compared it with others. Their website is informative and lists a variety of models for specific voltages etc.
The subs are actually down firing with a passive front. The speaker height is spot on. I’ve played with toe in, and am currently favoring no toe in for wider soundstage and better sound throughout the room.
One other thought; it appears that if you were to switch the subs, you would have the side firing drivers toward the inside. It may be undesirable, but I would try it. The result could be surprisingly good. No harm done and potential benefit.
Lastly, it might be fun to invert the ATC speakers or run them on their sides, perhaps with tweeters outward. This will change the system somewhat and lend variety to experiences. Of course companies will not advise, but this is your system and it's all fun. Take a look at my virtual system and you can see I tend to play around with such things as speaker position in order to get different experiences with soundstage. Such experimentation is informative as to how sound fields are influenced by design.
Nice, tight system; well thought out! Kudos! If your monitors are not at seated ear level, you may wish to play with the baffle slope a bit to tune them in as regards soundstage and center imaging. But it appears that with the stands they are in the zone. I presume you have played with toe in of the monitors. :)
Also in regard to the ATC monitors, consider a method I have used and endorse - in fact, using it now with a set of Wharfedale Opus 2-M2 speakers - which is to double (parallel) speaker cables, running two sets. It is a most efficacious improvement that keeps the character of the sound, but enhances it notably.
Just make absolutely sure all connections are perfectly parallel, no crossing over of terminations at amp or speakers. I triple check such connections and never change gear when tired, because mistakes can be made. Typically I keep on hand both spade and banana terminated speaker cables for that purpose. :)
