Parasound A21 and A21+: Significant Improvements in SQ?

These are the changes made in detail, all bodes well for what your asking of the new A21+

Improvements made over the older A21.

• The power has been increased from 250W to 300W into 8 ohms, with comparable changes into smaller impedances.

• Power supply filter capacitance has gone from 88,000ÊF to 108,000ÊF.

• Signal/Noise is up from 112dB to 115dB.

• Total harmonic distortion at full power has been halved, from 0.2% to 0.1%; at normal listening levels it's claimed to be below 0.03%.

• Channel separation at 20kHz has been increased from 63dB to 70dB.

• The capacity of the transformer has been increased, from 1.2kVA to 1.3kVA.

• Partly as a consequence of the above, the amp got heavier: 71lb, compared to 60lb.

• Cosmetics were updated with aluminum endcaps and gold highlights.

• The same heavy-duty speaker terminals used in the JC 5 stereo power amp were added.

• Internal audio connections were upgraded to gold on gold.

• The automatic turn-on circuit was improved.

Cheers George

Also Is the new A21+ a John Curl update?

To me it wouldn’t matter, as those updates are just bigger, more, better things to do to it, everything has a monitory max to it, the A21+ has more build budget so it's got higher retail cost.
Most of the differences are just over engineering differences, hence the higher costs. But the basic topology of the circuit design is still John Curl’s, and that’s the heart and that’s what matters, the sound signature should be more similar than more different.

Cheers George