Old is best, my whole system bar Shanling CDT-100 is 2nd hand and I have never had reliability problems. Go for the large, reputable, established manufacturers. I have always had helpful fast response from Pass and Conrad Johnson, but I have heard good things about small new companies especially Rogue, Monarchy audio.
I 2nd the view about Pass labs power, I use the Aleph 3, clearly only suitable for sensitive speakers, mine are Living Voice Avatars. I also use a Conrad Johnson Prem 17, but some of the older premier models 10/14 are very cheap and excellent.
I enjoy buying used, there's more searching and interest, going to your local dealer is boring.