McIntosh- Sweetest, Smoothest sounding Solid State ?

Yes, the Sugden amps have an organic sound, especially the Masterclass. 

Since March 2020 I’ve been working from home and have music on much of the time. I’m actually thinking about getting a Sugden A21SE to use when I’m playing music while multitasking. My tube amp has a fairly pricey compliment of tubes and I cringe thinking about reducing their remaining life while not always listening intently.

...my other thought is a Pass SIT-3 when not running my tubes.

here is truly one of the sweetest solid state units (and with good, real world power), for a song... i have zero affiliation, don't know the seller at all -- so a prospective buyer would need to do proper due diligence, and not mind an older unit that may need a little care and feeding over time

https://www.usaudiomart.com/details/649762917-bedini-ba-801/

It depends on which McIntosh amp. Not all of their amps are created equal. In fact McIntosh makes a ton of stuff I would never buy, having said that I have been a loyal fan of their amplifiers for many years. My system changes from time to time but my amplification has never changed, McIntosh gives me truly no worries, and to this day after almost 15 years of use with no problems ever my Mac MC352 power amp still sounds amazing.
Matt M