Mellow speakers for a digital piano

Or you could just try turning your speakers outward at a 45 degree angle so you don't get the full brunt of the highs.  That would certainly be a cost-effective solution.

Wow .... now we are getting somewhere ... 

These homeopathic/Rube-Goldberg solutions may be just what I need.

LOL ....

You can be sure I will try them all.

Desperate times and all ...

Yamaha NX-N500. Lovely sound, smooth, reminds me of Era/Peachtree D4. I have Era D4 hooked up to Yamaha RX-A1060 in my sunroom and NX-N500 in my kitchen. Love them both. Nice but not boomy bass for the size.

About $500, amplification included, plus a really nice wireless music solution. I take them with me on vacations.

If this is just for home use, I would start with a tube amp of about 30 watts, like a Dynaco ST-70 or the like, and find a set of speakers that are easy to drive so that 30 watts means something.

My JBL JRX215 speakers that I use for my keyboard rig are 8 ohms and 97 db; they are easily driven by a 30 watt tube amp. On stage I use 500 watts per channel, but there is no need for that at home. You can find them for $300 each on ebay. They are not the last word in resolution, but they sound surprisingly good with a decent signal. Not much output below 40Hz.

You might also consider a set of JBL L-100s...

You might want to process the sound a bit. I would not use a mixer, but I would consider a digital reverb like this one: http://www.alesis.com/products/legacy/nanoverb2

JBL used to make a very cool keyboard speaker that someone I worked with in the early 80s used. It had a shallow but tallish cabinet, a 15" woofer and one of those "bullet" tweeters.