Thank you all for comments. I sent my TRIO 300 for an XD upgrade directly to Krell. It turns out they upgrade older models to XD for $1,450.00 + shipping costs. The customer service at Krell was amazing. I got a call from the Krell’s CEO with an update and he spent good 10 minutes with me on the phone explaining advantages of XD. He also gave me his cell phone number if I need anything in the future or have questions. Truly remarkable. Amp came back looking brand new. They also included XD badge on the front panel.
Now, when it comes to the sound. To be honest, I am struggling to pick up on the difference. Maybe if you could switch XD on and off if would become more apparent, but in my opinion this amp sounds great with or without XD upgrade. Perhaps I should upgrade my speakers to take full advantage of this amp, my 10+ year old ML ESLs may be looking for new home soon.
Can anyone recommend speakers for this amp? The two I am thinking of are ML 15A, or KEF Blade 2s