new life for pa500

[maintech]

I just downloaded a fresh copy of the user manual for the pa500 & I'm delighted to note that I can use Mobilesheets with it. I bought the pa600 when it came out & it had an additional note regarding Mobilesheets, and have used that to expand the joy of playing (not well, but enthusiastically!).
I'm taking the pa500 south this winter and will leave it there (snowbird who wishes to fly instead of driving from Ontario) & having Mobilesheets will make it that much more enjoyable. I would like to explore adding a digital sound device like the Keytron SD2 for experiencing what it could do to put a sparkle into the pa500 as Fransman had experienced back in 2011, but I understand that stuff has changed since then. Anyone have suggestions that won't break the bank?
Thanks in advance,