I've owned AVA gear since 2009, which makes me experienced, but not the longest going on this board by a long shot. I've been very happy with it over the years, and I've done a combination of ordering new from Frank, also taking advantage of his "quick ship"/used pieces on hand, and I've bought several pieces from the normal online used markets.
For anyone who is new and checking out AVA as a brand, the only thing I can say is just jump in at where ever you feel comfortable. I've bought things that were top of the line at the time, and also from his lower end, and they all sound fabulously good. I've bought old pieces guys had in their basement and weren't using as much, and it still sounded great. Overall the equipment has been bulletproof. Don't feel like this is a brand where if you can't buy the top range of current production you are selling yourself short, there is a huge amount of value in anything this company has produced in the last 40 or so years. Some of my most treasured equipment is among the lowest priced he makes, the T10 RB and the SET120 Control Amp.
With that in mind, I did have a hankering to upgrade my 2 channel system attached my main system in my living room, but I didn't have a ton of money to blow. This system pulls double duty as a tv and audiophile system, and was a brand new Insight stack (EC pre w/phono, DAC, and 440 double die amp) a decade or more ago. I chose to go solid state because between my kids playing video games, the wife or I blasting music as we do our chores, or just regular tv/movie time, this system sees a TON of use. I didn't want to have to change tubes all the time. Enter the Vision RB.
I'm aware that the Vision RB is probably several years old now in 2022, but its also several years newer than the Insight I had purchase back in the day. I was expecting it to be worth the money, but I was actually astounded how much different it sounded. The overwhelming impression that I got as a "casual audiophile" was the sound was just more open and enveloping with more clarity and dynamic punch. Needless to say, I felt immediately it was worth the money that I had spent on the upgrade. I pretty much regarded that system as "done" using a decade old amp/dac, with a very nice new preamp.
About a week or two ago, Frank posted a DAC MK 5 on his used page, and somehow it wasn't magically taken. I know I have a better chance of buying authentic dinosaur eggs at present than that particular piece, so I quickly rationalized the instant purchase as "it has a USB input" and it also accepts TOSLINK so I could do away with the converter I had hanging off my Insight DAC. And it will probably sound a bit better than my Insight DAC. A bit better was underselling it. This was also a very substantial upgrade, and I feel very fortunate to have gotten it at a used price. The sound out of my main system which I had considered "done" only a couple of months ago with the upgrade to Vision RB was even more lifelike and smooth, no detail lost, and just overall plain fun to listen to. Functionally I enjoyed the upgrade because now I have several possible inputs on a selector, I have no cheap TOSLINK converters in my chain, and I can now plug my Macbook Air straight into the thing and pump up the jams from my Foobar2000 playlists that I use everywhere else so I don't even have to seek out a streaming solution or manage 2 sets of playlists.
Within the last year or so I have bought several pieces from Frank: a T10 RB, a Vision Phono, a Vision RB, and a SET 120 control amp. All of these pieces are within the ~$1000 price range (the phono half that) and can often be found for less on his quick ship page. These are a tremendous value for the "everyday guy" who enjoys the audio hobby. I have three kids and not an unlimited budget, but I can swing gear like this and it sounds awesome. AVA powers my headphone listening at work, my workout room at home, my wife's tv/vinyl setup in her sewing studio, and my main home theater and I'm glad there's a company like this that produces quality gear for me. Maybe someday when I have 3 grand, I'll decide my system isn't as done as I thought and upgrade to a pair of monoblocks.