Digital transports... this is war torn territory. To some digital is digital and it will not mater and to others it makes a huge difference. In your case I would argue that it will not make a difference.
I have a 800v4DAX, a formerly $20,000 DVD/CD player from Meridian. I needed to replace the drive and found out the same exact DVD_ROM drive is found in the $98 Apex DVD player ( DSL-720A ).

The magic of Meridian isn't found in the commodity of laser mechanisms but rather what happens after. Since you have an UltraDAC the processing on your DAC will be more than sufficient. The only caveat would be if there is some sort of digital reconstruction the better transports are capable of after reading the disc. In this regard I am not an expert and can offer no firm answer.

In the end, with an UltraDAC you would get no benefit of a CD player's analog output so you can hone in on the 598DP and the 500 transport in the 500 series or find a good price for a digital only 800 series player to match your UltraDAC. I have seen the used digital 800 series have been as low as $1,000 USD. If you come across a 506, 507, 508, 588, 586, or even 596 for a good price you could take advantage of their digital outputs and run them as a transport (or even re-digitize their analog output <also controversial> for the old school Meridian sound).

558.2 amp, Meridian A500 speakers, M2500 sub, Director & Explorer DACs