Jeff Rowland or Mark Levinson???

It depends what kind of listener you are.
1. Long term Listener
Here is the Rowland much more satisfying, it is very musical, maybe one of the most musical Transistor Amps available. Doesn't matter which model. They are all good.
2. You know nothing
but you want to walk on the safe side, believing in revolutionary technical progress ( all 8 months ), would like to have the respect from your neighbours, here you are right with ML, specially when you like listening to Test CD's, splintering glass, Bing-bang-boom-music and you like to impress your friends with that.

I know some owners, who love these amps.

Thomasheisig, if you were aiming at getting a little spirited debate going, I think you hit the mark. I don't share your opinion toward ML products, but I am a Rowland owner. In the price range that I set for my purchase, I found a used 8TiHC to be my choice over the ML 335 or 336.

My reason for posting a follow-up is that in JCB2000's thread posting, I interpreted his statement that (the) "Mark Levinson is 150lbs (and) you just can't take one home to try" to mean that he is not auditioning a Rowland 6, 8 or 9, whose weights are comparable to 33X series ML, but more likely a 10, 12 or 112 weighing in at less than half that of the ML. The reason this is significant IMHO is some folks have stated sonic differences exist between "older" JRDG equipment and the new amplifier designs. Most responses have referenced older model JRDG amps as being their choice over ML, which is fine, but I am not so sure that JCB2000 is listening to any of those. In fact, JCB states a desire to buy a new amp. Blbloom's post is the only one thus far that has spoken to current JRDG equipment, and he discusses the integrated Concentra.

JCB2000, which amps are you auditioning?

Well it looks like I'm going to rock the boat a little on this one. I've owned a Roland Model 5 and replaced it with Mark Levinson reference 20.0 monoblocks. Now, keep in mind that even on the used market there is a significant difference in price, so I'm not comparing similar cost products. When I made this change I did so based on listening. I agree with the above posts that the Roland is very tube sounding and smooth, but it also had some limitations. The speakers were Martin Logan Monolith IIs. They are difficult to drive when not biamped. The Roland did not have the bass control particularly when the panel were exhibiting very low impedances. The Levinsons (while lower powered amp) did a much better job in this area.

I think it's important to evaluate what kind of demands your speakers might have and what combination you will get in the end. If you have an overly polite speaker, the Roland might sound a little to smooth. Also, if you have a very difficult speaker to drive like the older Martin Logans, that too may not be the best with the Roland (although I've only used the Model 5, other models may have been better with my MLs). For the majority of speakers out there both products are excellent and will likely deliver long term satisfaction.

Cant go wrong with either. I think speakers will dictate which is best. The home test is the best way to make the choice!

I agree with Abstract7 that with a "polite" speaker the Roland is likely to sound a bit warm and rounded. I tried the Roland 10 & 112, the Levinson 336, and a few other amps with my Dunlavy 4's. I found the Rolands to be "soft" sounding with a pleasant high end, but lacking in bass handling. The Lev had more slam and authority, but struck me as still a bit soft on the bass control. The mid and hi character was smooth and controlled.

Having said that, the build quality of both are excellent, and prices for stereo units are often roughly in the same ballpark for similar power (but this can be model-dependant, and monoblocks are a different matter altogether).