Disadvantages of buying old solid state.

+1 on Schiit equipment.

Balanced interconnects are the best because of noise rejection, but unless you have very long runs or your wires are a tangled mess behind your rack, you probably won't be able to detect the difference.

One of the problems with older products, especially S.S. is that the parts may no longer be available. I am having a problem with an older ARC S.S. amp that may be impossible to remedy. The other problems is when I opened this unit up I saw exactly how stupid the design. Awful opamp module running the whole works or at least the works that matter most. 

Unless you have tried a .8 amplifier in your system I wouldn't dismiss it. Different speakers, room, positioning, ancillary equipment, etc. impact a system's sound.

Also, IME, different amps in the same series sound different in the Pass lineup.

I have been buying used equipment since the 70's and have had very good luck. I am technically inclined so re-capping or replacing a transistor has never been an issue. That said I do have some very good equipment and it has not cost me an arm and a leg. I recall going to the mall or stereo shop in the day and drooling over the very expensive equipment and realizing I needed a car, refrigerator, or clothes for the kids more than an amplifier, so I fed my addiction with used stuff, much to the chagrin of the pompous stereo sales guy. Being a tech I have found the older equipment to be better built (50's, 60's, 70's and 80's) than modern is. I have been horrified to open up an amp that cost thousands and is built the same as one that cost hundreds. Even the  modern tube stuff is based on designs from the 60's or earlier but the packaging is impeccable. I hear people say that ss parts are not available, well not really. There are a lot of cross references you can make. Caps, transistors and inductors are the same now as in the 60's. Do not be afraid to get the old/used gear. If you are not technical then have someone who is look at it. If it has decades on it then plan on swapping out the filter caps in the power supply and give the transistors a check while you are in there, or have it done for you. The best amplifier, speakers, or any audio equipment is the one you like the best. I love my music and I will never be found sipping expensive wine and listening to the philharmonic play Mozart on a system that costs more than a house in Mississippi. Instead you can find me with a beer, smoking xxx and attempting to melt my coffee table sonically with some Deep Purple or Whitesnake, but it sounds astounding from my Dynaco gear and some Timeframes, both of which have been trashed on this very forum but I love them. Also keep in mind that Haffler (Dynaco), Carver (Phase Linear) and Pass (Adcom) all worked for someone else before they set out on their own, and their designs are in a lot of old equipment there for you to grab, restore and enjoy for just a few bucks. 

Caps, inductors and transistors are not the same as in the 60s. They may measure the same but they do not sound the same. Plus you have significantly more good choices now than back in the day. You could take the exact same Dynaco circuit update it with better innards and it will sound better. Some say it will be unrecognizable. So, with all due respect, you should listen to some of the more modern gear because I think you might be very surprised. This would especially true with more modern speakers.