Not bad at all
I picked one up after flipping one Wouxun because of horrendous audio and being somewhat unhappy with a second KG-UV920R-A because of raspy audio and slow tone squelch release. The firmware was nice and the hardware pretty. But, I wanted something that didn't hurt my ears.
All in all, it appears to be a nice radio for the price. Got it from HRO who had it for $20 cheaper than everyone else. They also threw in a separation kit which is going to sit for now. I did buy the software, which ends up being RT Systems V4 and cable. I've been quite happy with RT's software for ICOM and Yaesu, so this was no exception. There is some quirkiness particular to the DB-750X like the 'Squelch Mode' selection in software. It seems to be redundant to the 'Tone Mode' selection or I just don't understand it. Sadly, the Help file is the one common to all V4 software, so you are on your own for the individual header selections and menu items. One thing that the DB-750X does not have compared to the rest of the Chinese radios is the ability to have one display show alpha characters and the other to show frequency, I find it helpful if my shorthand for the alpha falls out of my head. I can usually remember the frequency. So, for a workaround, I left the amateur freqs to display with frequencies and the public safety ones on alpha. Works for me. Something that the radio does have that others do not is both 2 and 5 tone encode/decode. Our EMA still uses pagers and 2 tone encode for warning siren activation, so this was a Big Deal to me. The variable/mixable display colors are a unique solution to a nonexistent problem. Ultimately, I ran all three up to max to produce a white display with a slight blue cast. Operationally, it performs as advertised. Audio both transmitted and received is very pleasant. I'm going to forgo an external speaker on this radio for a while. The buttons are a little small and you really have to be sure of what you are pressing. The PTT on the mike is a bit finicky and wants to be hit squarely to function. The VHF receiver has some strange artifacts which cause the S meter to bounce on certain freqs. I live in a rural area, so I'm discounting intermod. Again: it's a $300 radio.
I'll leave the test equipment gyrations for others. What I have found so far, I (mostly) like. The Wouxun is going on the for sale block and the DB-750X will become the radio that I put in the car when I need it for storm spotting and such.