Wow.... you have three different posts in two different forums...... I'll try to answer all three of them for you. First of all you asked about hooking up the S-80 to the computer with either a "to host" hook-up or to the joystick port.... I've never tryed a "to host" cable (in fact I've never even seen one) I use a cable that goes to the joystick port.... it works fairly well, I'm no expert, but I haven't run across any problems. Either way should work... although I would probably say go with the joystick method.
Second, you asked about saving songs to play on the S-80..... I think if you hook up the S-80 via the "to host" hook-up you can download midi files to the SmartMedia card from the computer that way (don't quote me on that) Or I have seen something that hooks up to the computer and saves files to SmartMedia cards (kind of a zip drive sort of thing) I would guess you could save midi's on the SmartMedia cards this way. I think the drive was about $100 or so.
And last is this question here..... Obviosly the feel of the semi-weighted keys on the XP wouldn't be as close to an acoustic piano, if that matters to you. As for the expansion boards, I don't know if Yamaha is planning to come out with any more boards. Roland is probably nearing the end of their SR-JV line with the new SRX boards coming. So what's out there now is probably pretty close to all that there is going to be. The main thing to consider about the expansion boards is this..... All of Roland's boards only add sounds, just a bunch more patches and waveforms. On the other hand Yamaha's boards add new synthesis engines.... one adds a Vocal Harmonizer, another an acoustic instrument modeler, another adds more polyphony, etc. Now as for arranging and recording your own stuff.... I would say go with the XP, it has a sequencer onboard the synth, something which the Yamaha S-80 does not have. This would allow you to compose stuff on the keyboard without having to hook it up to the computer...... also you can save songs to standard 3.5" disks (Again, don't quote me on this, I'm like %90 sure) This would be a whole lot easier than the S-80's song playback method.
So it all comes down to what's most important to you... If you want the full 88 key, weighted board... keep the S-80. If you want to add some new synth engines like the Vocal Harmonizer or other ones I listed.... keep the S-80. If you want to have a huge library of sounds to choose from.... go with the XP. If you want an onboard sequencer.... go with the XP.
One last thing..... before you decide to exchange the S-80 for an XP or other synth.... first play with the other one and the S-80 side by side in the store. Check to see which one sounds better to you, and remember... if you want the sounds of the expansion boards, you're gonna have to pay for them. As for 88 keys or 76.... play some songs that are similar to what you might be arranging. If you find yourself running out of keys.... keep the 88 key board. Think how the feel is... can you live with the semi-weighted keys. If you just don't like the feel of the XP, keep the S-80. Hope I helped you out some.
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