Allen & Heath Xone:DB4, DJ mixer, controller and interface, 4-channel mixer, Quad Core FX effects engine, BPM detection for effects and loops, 3-band EQ on each channel, microphone / line input, 4 line Inputs (2 for record player selectable), 4 digital inputs, USB sound card (24-bit / 96 kHz) with 4 input and 4 output channels, dual Xone filter system, built-in looper with up to 4 loops of 1/16-Bars
I have had this mixer for about 2 years, I use it around once per week. I have had couple of problems with it. I returned the unit already twice. I don't trust the mixer anymore, the quality is not what I was expecting. I thought that Allen & Heath was one of the most reliable ones, but I should have gone with Pioneer. Bad purchase I would say.
I'm really impressed with this mixer, the FX are genuinely and clearly tailored to both be genuinely useful for DJs and to provide a tasteful range of options.
As a promoter I really appreciate how most settings on most fx sound alright, unless you push them to extremes. I was worried about putting this in the hands of DJs and potentially seeing them use the FX to cover up mixing mistakes, or just overusing them in general. Where FX on competing mixers may annihilate the mix, the db4 enhances it. After a while of using the mixer I came to treat the FX in a similar way to EQ, for fine tuning timbre, rather than dumping a sound on top of the mix.
The controls are also brilliantly laid out, without reading the manual everything made sense within a few minutes, the build quality is superb, and the feel of the faders/pots ideal.
The mixer worked perfectly with my CDJ900 nexuses out of the box, so no worries there. I've been using the digital connection which works perfectly. I also appreciate the option to knock some decibels off the record out, so no need for an attenuator.
the only downside I can think of is that you can't chain FX like you can with a DB2, hopefully this will come with a later firmware update.