My tests differ:...
The DP-02cf's internal preamps are neutral sounding, but with a decidedly underpowered top end gain, which is way below the top gain on a typical analog Portastudio (or mixer) of any sort I've tried to date, (and that's a lot). There's no way using the internal pre's you could set a typical mic onto V-high gain and back up from the mic 4 or 5 feet distance (distant or room mic) [for vocals or acoustic guit.], as you could do using any other Portastudio I'm familiar with, or mixer-front-end.
The DP02cf's gain top end using an SM57 on XLR required vocal or ac. guitar distances of 6" or less for decent levels. 12"? Forget it. A Shure BG 5.0 (batt pwrd condenser) tested out at roughly the same amplitude, but with noticeably better sound characteristic than the 57, which sounded boxy and muffled in comparison. An AT Pro 2a Hi-Z dynamic mic with 1/4" plug actually gave more gain than the SM57 and BG 5.0 on XLR inputs.
I tried a TASCAM PE-120 battery powered condenser mic on XLR, an A/T "Bite" XLR dynamic mic, and another unmarked A/T cheapie XLR mic, and the maximum gain of the DP02cf's preamps were woefully inadequate. The PE-120 at least is a high quality recording mic, less so for the "Bite" or other unmarked A/T mic. The crappy gain achieved using these mics would prevent using these on the internal pre's for your typical recording.
If you're into (acoustic guitar) very close mic'ing techniques as a rule, this unit's preamp gain is barely passable with your typical mics (like SM57). (Mic'ing a GUITAR AMP would be do-able). As an adjoinder, I was easily able to lite the "OL" LEDs on the unit by using a guitar or bass plugged in. However, with a mic plugged directly in it was virtually impossible to lite up the "OL" LEDs. Well, not impossible, but it required effort.
A little peeve of mine arose in that the DP-02cf's power supply module puts a noticeable low level hum element onto input signals, most obvious on the Hi-Z 1/4" plugged mics, but also on several of (apparently less well shielded) Lo-Z XLR mics. Fortunately, the SM57 was virtually free of this hum, as was the BG 5.0. Better shielding is what I attribute this to. However, the power module gives a notieceable hum whenever in use, even to external units (like my 244). This problem has me contemplating selling the CF. Undecided as of yet, TBD.
I feel the SM57 is not a mic that sounds good right out of the box & plugged straight into the board, but requires use of EQ inline to get a decent or natural sound to the recorder. I'm accustomed to EQ'ing an SM57 prior to going to the recorder, with which I've typically gotten good results. The DP02cf's lack of front end mixer of any sort is a big drawback of this unit and any other similar unit with plain "A/B" input-to-track architecture.
What I think of the basic utility or need for EQ of the 57 is probably grist for another post, but thru these tests and this description I've decided absolutely that the DP-02cf is best when fronted with a high quality mixer, or at the least an external preamp. This opinion I've held solidly prior to buying the DP02cf, but have borne out worse than expected thru testing.
So far, I've fronted the DP-02cf with a Tascam 244 (mixer section), and there's a night/day difference with the flexibility and high end signal you can get into the DP-02cf. The 244's preamps have high enough gain to back up an SM57 (or other mic) 6' or more to be used as a room mic, and it just howls with high gain,... way more than adequate. The 244's preamp top-end gain seems super-hot as compared to the DP-02cf's preamps, which sound wimpy in comparison. EQ and bussing are features I'm accustomed to using in the recording process too, ala' the classic hi-end analog Portastudio or other mixer/recorder system. I'm old school l like that.
The audible 60Hz hum induced from the DP-02cf's power supply module was only accentuated with the 244's high gain preamps, tho' is barely noticeable on the DP's low gain pre's. I'm thoroughly disappointed with this audible flaw. I think it's a poorly shielded supply module, and not a "defective" unit, per se, worthy of going thru the "exchange" process at MF.
At this time I'll hold onto the CF and try to minimize the audible hum. It's funny that it was not noticeable on the SM-57, probably due to the solid grounding and shielding of the 57. The construction and shielding of the particular mic seemed to make a big difference,... but I have a fairly large selection of low-Z cheapy mics, some of which hummed outta this world. My stash of mics bears out further testing on the DP02cf, as yet TBD.
I'm so far holding onto the DP02cf though by my standards it's given me lackluster results. I'm also against the inherent need of a so-called "Portastudio" to beg the issue of needing a front end mixer, thus making it no longer a one-unit self-contained solution,... the opposite of the definition of "Portastudio".
My 2¢
