There were 2 reviews I got off it re the USB:
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The best grand piano sound of any digital instruments on the market. Great Church Organ, Chorus, Digital Piano, not impressive strings. Great internal amplifier and speakers, perfectly sufficient for use at home. Don't get me wrong. If all your need is a great grand piano with some fine additional sounds, this may be the best instrument you can buy. The Grand Piano sounds and feels the best of all instruments of this kind on the market and I believe I've tried them all! However, there are some problems, too. First, unlike most competitors, P250 is totally non-upgradable. No expansion boards, no extra memory capabilities. No hard drive, no memory cards Internal memory capacity of the P250 is miserable by today's standards. The built-in synthesizer is very basic, good for beginners only. USB port on P250 is the old, slow v. 1.1. My outmost concern is as follows: I own a new 64-bit computer system. As you may know, 64-bit Windows provides support for up to 128GB of RAM and up to 16 terabytes of virtual memory, which in turn makes it an ideal system for sampling-based music production. The problem is, Yamaha does not have 64-bit MIDI and USB drivers, thus rendering their instruments incompatible with 64-bit computing. My Conclusion: This is the best-sounding and best-feeling digital grand piano on the market today. If this is all you need, by all means buy it!
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Yes if you want everything in a top of the line digital grand piano, then this is the item for you. Since getting one, i am very happy with the unit. If you want to do good sound record quality, then make sure that you also get Sonar 2.2 program, & a M-audio 66 break out box with serial connection (usb sucks) it can record multi tracks & MIDI at the same time. It is portable, but at 66 lbs a bit big. Software for MIDI connection great and quick. Speakers very nice at loudest setting. This is a must have.
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What would that mean?
Right now all I want to do is to be able to move and save the files onto my notebook....I guess that would be useful for sequencing too in the future since that seems the better alternative - so I guess the ability to save onto a notebook or hard disk would be necessary?