How To Update Traktor Scratch Pro

Native Instruments (NI) released updates for its digital DJ products, Traktor Pro and Traktor Scratch Pro. The update brings Advanced Relative Mode to Traktor Scratch Pro. All users of TRAKTOR PRO 2 and TRAKTOR DUO 2 will receive a free update to the latest PRO 2.5 software as soon as it is available. The updated software version introduces the innovative Remix DecksTM, which allow DJs to creatively remix and rearrange tracks.

How To Update Traktor Scratch Professional

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Traktor Pro 2 Download With Crack

I purchased Traktor Pro a couple months ago. I have Serato and was happy with it, but now I'm consolidating my setup and since I'm learning Traktor I might as well use it with my tables instead of having two different programs.
How much is the upgrade from Pro to Scratch Pro?
I'm also concerned with the hardware part. I know it comes with an interface. Is it only an interface for two turntables? Can I upgrade to the A8DJ so I can have outputs for 4 decks and still use the timecoded vinyl? Or would I need two interfaces for that?
Thanks for any info!