I'm going to try the M-Patch2, from SM-Pro Audio. This is a slight upgrade from the original M-Patch(Still available, I believe?) design, which now includes a headphone jack/amp.
Basically a "patch bay"/attenuator(A box with switches and inputs and outputs), that I'll plug my powered speakers into, my Mackie mixer and my sound card - direct. Monitoring should be unencumbered by any "extra" circuitry(Assuming the M-Patch is rather "Pristine", itself?), at least no more amps/eq, etc. It's not quite "in" the US, yet, so I'm ordering direct from Australia. They say it should be available here in about 4 weeks(8Th. St. Music, in Philadelphia, among others, is a dealer.).
As far as I can see, this is THE gadget that I have been waiting for for several years..? THE place to plug the phones and speakers into AND a neat-o, very convenient little "patch bay". For a price of around $150(US), I'm going to buy one and hear for myself...
Sorry, I can't find my link to the place, now... I'll check and post it in a minute.
TG