TurntableSpin

In a nutshell, the X² is the CDX and TTX combined in a neat and good-looking package with a few key differences: the CD section has no built-in effects, the vinyl section has no key lock or 78RPM (Who uses that anyway, right? But you can still do it with 45RPM +73% pitch.) And there's no digital output or MIDI at all. It's basically a no-nonsense, professional-quality CD, MP3, and vinyl player in one unit. I like to think of it as the ultimate transition device, since it can play everything from the oldest vinyl to the newest computer-based DJ software (using control records and/or CDs, preferably the latter.)

Getting all the basics out of the way, you've got dual start-stop buttons, 6/12/25/100% pitch ranges, adjustable braking & starting torque (0-6s,) adjustable scratch modes as on the CDX (for crossfader-less scratching,) CD program mode (to pre-select tracks to play in order,) key lock (for CD & MP3 only,) interchangeable straight & S-shaped tone arms, reverse & bleep switch, 45RPM adapter holder, BPM counter with beat LEDs, single ("auto cue" on CDJs) & continuous play modes.

Let me first mention that if vinyl is your main thing and you're looking for the best vinyl deck, you should really go with the Stanton STR8-150 or ST-150, as I consider those to be the best 'tables ever made. (They use the same floating magnetic drive system as the Technics only with higher torque, and they have key lock, digital out, 78RPM, etc. and are very heavy and rock-solid. Plus they come with a pre-mounted cartridge.) Don't get me wrong: the X² is a very good vinyl deck and you'll be very happy with its performance, it just lacks those couple of features to make it a great vinyl deck. (I ended up deciding to take the vinyl feature hit in exchange for more CD control in an all-in-one unit which cuts down on my load by two cases.) That said, the X² does feature interchangeable (straight & S-shaped) tonearms like its brethren, so it does have that advantage over the Stantons.

The X² has a CD-only drive (i.e. no DVDs.) It plays CD-Rs, CD-RWs (with difficulty, after warming up for a couple minutes) and of course pressed (store-bought) CDs. It accepts standard 12cm CDs as well as 8cm "mini" CDs (just insert them at the center of the drive by the LED.) Avoid non-round discs as they could get stuck. The discs can be regular (Red Book) audio CDs or MP3 data CDs. Numark says to avoid variable bit-rate (VBR) MP3 files but they seem to play just fine. (I only saw weird glitches when searching a long way through one.) It's always good practice to burn CDs you're going to use at a gig at the slowest speed possible no matter what it says on the disc. This causes a greater optical difference between the 1s and 0s on the media and makes it much easier for any drive (especially older ones) to read reliably. (It also increases the longevity of the data when exposed to light.) With MP3s, the X² will display the file name but no ID3 tag info, unfortunately.

There's no folder navigation either: the X² just goes through all the folders on the disc and numbers each playable file as it encounters them. You simply rotate the select knob to the file number/name you're looking for. You're limited to +50% pitch control while using MP3s, but can still go to -100%. Seeking/searching is a bit sketchy with MP3s of either type (compared to audio CD tracks) in that it'll take half a second to respond to a button press, play a bit of audio, then silence for a quarter second as it seeks, then a bit of audio, etc. (This is due to the fact that MP3s need to be decoded in "chunks" (especially with VBR files) and it takes a fair bit of computing power.) But scratching, backcueing, etc. all work just as well with MP3s as CDs (thanks to buffering.) You don't want to backcue too far though or you'll run out of buffer and just hear silence until the unit catches up.

A nice feature of the X² (and the CDX from whence it came) is the ability to change the key of the music (on CD & MP3 only) independent of the tempo. This lets you create harmonically-correct mixes, which are more pleasing to listen to. (Unless you're doing a Halloween party or something and dissonance is desired. ;) ) You do this just by holding down the Key Lock button and rotating the select knob to the desired key, relative to the original. Each click of the knob (and number in the display) is a half-tone. E.g. C to C#, E to F, Ab to G, etc. The selectable range is -64 down to +24 up.) When you release the button, the key change takes effect.

Another good time to use this is if you're playing an overly repetitive song (or running a loop) and want to make it a bit less monotonous: change the key 3 half-tones up to increase the apparent energy but still be in harmony with the original. This new key can also be locked just by pressing & releasing the key lock button (a lock symbol shows in the display.) Then the pitch slider only changes the tempo. A word on scratching with the key lock: it locks the key of the back scratch as well! Normally this isn't want you want (so make sure key lock is off before you bust out the moves,) but it can be used as an interesting variation.

Source DJWise