Primaluna gear was originally based on a Cayin TA-30 amp (which I had years ago) with the addition of Primaluna's adaptive auto-bias circuit (which is brilliant, by the way). Sound-wise, the Cayin was designed to bring back the glory days of tubes and channelled a vintage design, can't recall which brand. The transformers that they had on the original amp were quite good and the sound quality was not as vintage as the design brief seemed to say - the treble was pretty well extended compared to the old stuff.
They also ran the output tubes conservatively, not trying to squeeze too much power from them.
However, these were intended to be budget amps for middle of the road systems and their lowish power output (except the 70 watt monos) means you need fairly efficient speakers if you like "slam" and dynamics and decent control of bass.
So, Primaluna will work for you if your speakers are quite efficient and you will get best results if the speakers have a fairly benign impedance curve with frequency.
Oh, and the build quality of these amps is exceptional - I believe the factory in China used to produce military products.
The AR's are supposedly higher in absolute resolution and have the power to drive less efficient speakers to realistic levels. However, they run the tubes very hard and a lot of modern tubes are just not up to the task. I believe AR actually has to buy stock and do their own testing to figure out which ones will work without arcing over (CJ have to do that same thing) :) I have often wondered what it would take to reduce the operating point to a safe place for modern tubes as well as how much output power would be sacrificed...
I expect the AR amps have a lower output impedance, thus handling speakers with more complex impedance curves.
Additionally, the AR amps are a modern design rather than a copy of an old one with a few improvements made for reliability.
Don't shoot me, I am just musing :) We are talking about vastly different price points between AR and Primaluna, although age tends to balance the difference somewhat.
I have tried the Jolida (another decent Chinese brand) JD1000BRC amp and it runs the tubes fairly conservatively, but it just isn't an audiophile amp as it rolls off too quickly at the top and struggles to produce mid-bass in speakers that are almost purely resistive. Given the right speaker match, it could be an option though, and it is reasonably well made and easy to service and has a warm and friendly sound.
Rogue Audio amps are probably closer to the AR sound and they are a bit more reliable, from what I hear. They do also run the output tubes pretty hard.
I have not heard them, but I hear that the Bob Latino Dynaco based (VTA) 125 watt monos are very good and reliable amps indeed and they are quite nicely priced.
http://www.tubes4hifi.com/bob.htm#M125Many other tube amps from small manufacturers are just downright horrible copies of classic amps with cheap and nasty output transformers; in some cases they include design errors and in others are downright dangerous. I have repaired many and added safety grounds, etc...
