NOTE: If you are monitoring directly off the pre through headphones, etc and if you are playing the source instrument (singing, acoustic guitar, whatever) yourself while engaging/disengaging the low cut, the phasiness your hearing is most likely an illusion caused by hearing the full low end of the instrument itself then hearing it with the low end cut out through your cans. Makes sense? No, i didnt think so.
Heres a good trick to find out whats really going on: record a dry track of whatever, prefferably something with a wide range (acoustic guitar is great for this), then feed it back into the DMP3 and listen to it while engaging/disengaging the low cut switch. ONLY MONITOR THE SIGNAL COMING OUT OF THE PRE AND NOT THE PRE-RECORDED SIGNAL COMBINED WITH THE DMP3 SIGNAL! If you are still hearing something wierd, then the low cut circuit is most likely the culprit, if not then all you were hearing is the instruments' low end vs. the lack of low end of the shelved signal.
Pheww i hope that makes sense. lol
Also keep in mind that cheaper gear is cheaper because someone cut a corner somewhere...point blank. Phase incoherencies happen anytime you put something in the signal chain. Phase (in a nutshell) is basicly a very small amount of time or delay between one signal or another, or between the source and the output. I've noticed that some cheaper gear actually uses more bullshit in the circuit than is necassary to achieve a desired result rather than using the equivelant one or two parts because the parts are expensive. However, every component you add in a circuit is just one more part the signal has to pass through before it reaches the output, thus causing some phase problems.
IMHO, phase can somewhat be compared to latency in the digital realm in a sense that the more gear you have in a chain, the more out-of-phase your end result will be (be it a very small difference).
Anyways, if there ARE problems in the low cut circuit of the DMP3, its probably phase-related, and id be willing to bet its because of poor design and was a quick afterthought to the design of the preamp. Not a real big deal, but something that is worth noting.
Someone shoot me for babbling and correct me if im wrong please, i hate sounding like and idiot. lol Hope some of my ramble helped.
the kid