I have owned the JOR and currently own a DA30 and DA60.
The DA50 is more or less an update to the DA30. A bit analogous to the update that the JOR was to the Orchestra, and today, the way the DA88S is to the DA60. So, while I have not owned the DA50, I can give you a rough perspective on the differences between the JOR and DA30, which will be close to what you are looking for.
First, Jadis integrateds seem to be as good as things get in terms of producing music, and the enjoyment related to the emotions of having this in your home. Secondly, a rule of thumb that was told to me, and seems to be true in my experience - even the smallest Jadis is still VERY much a Jadis, but as you move up the line, you get more of it. That more may be more power, more resolution, more refinement. But, you will get the essence of everything that is beautiful about the way a Jadis makes music no matter what Jadis you buy.
The JOR features:
- passive preamplifier section
- 2 12AX7 and 4 output tubes
- ability to run EL34, 6CA7, 6550, KT88, and KT90 ouput tubes
- Class A/B operation
- manual biasing procedure, and complex to boot. The amplifier must be taken apart and reassembled, which once the procedure is understood, is the most difficult part
- 40 wpc with EL34, 53(?) with the larger tubes
- bass and treble controls
The DA50 features
- active preamplifier section, using 3 12AU7 tubes
- 2 12AX7 driver and 4 output tubes
- I may be wrong on this, but you should use the larger tubes (6550, KT88, KT90)
- pure Class A autobias circuit
- 30 wpc
Now, for my own subjective opinion...
The JOR is definitely what I consider the most astounding product in high end audio. A much overlooked product, it can sound just about as wonderful as anything in this hobby in many regards. I believe it is not really understood because of Jadis not being available for people to experience and also because it costs "only" $3500. If it's a question of value - JOR versus DA50S, the JOR wins. But, the JOR wins pretty much no matter what it is compared to from a price/performance standpoint in audio.
With the right output tubes, which I consider to be either JJ KT88 or JJ E34L tubes depending on your priorities, the amplifier is simply magical sounding. Running the JJ E34L tubes, I got perfect midrange out of my unit, with my Coincident speakers. I have NEVER encountered that from any other high end audio combination. It brought tears to my eyes. I think the passive preamp lends a lot to this. Bass was not exceptional, but I was happy enough. Treble was also wonderful. I have owned several mono tube amplifiers (including the AtmaSphere M60 MKII.3 that I own currently), but surprising as it is, the JOR produced the best imaging I have encountered in an amplifier. And, though high end taboo, I loved having the tone controls, they let me shape the music to what I thought sounded best from source to source and CD to CD. I realize that leaves me open for criticism; so be it.
The person I sold it to has the keenest of ears (he may even check into this thread - hope he does), uses it in his second system, and is used to the finest of audio equipment (what he uses in his main system). It's the product he ended up with after moving through many products along the way. The JOR looks to be the piece that will be there forever. He seems to consistently be at a loss to explain how good this amp is, or where exactly its ceiling is. I feel the same way. Incredible!
I'll speak of my DA30 (actually a Defy DA30), and we can extrapolate that the DA50S would only be better than what I am saying. Also, I must say that my DA30 is an extremely old unit, different in many ways from what the current DA30, or the DA50S is today. It may have been the first integrated Jadis produced. I have heard that this model has more purity sonicswise, at the expense of thermal stability and ultimate power, but I have not had a newer DA30 or DA50S to compare it to. Also, my DA30 has been "upgraded" by changing the bias resistors and caps, and possibly other things. And, it may well have shifted the sound (my friend who owned it previously told me the improvement was real). Though I do have my DA60, and while I have not worked it all out as of yet, there are some real differences between it and my DA30 and the JOR.
With the DA30, you get the active preamplifier section (which, as we know, preamps exert an incredible impact on the sound), larger transformers, and a different circuit. It's quite different sounding than the JOR, but retains a special thing that I have only heard come out of a Jadis, which appeals to the heart. Jadis products are best enjoyed by folks who get the emotional end of music, and are less concerned about the way things look on paper or measure.
The DA30 fleshes out the bottom end, lending a rich, liquid, full and voluptuous sound that does not exist much in high end audio today. Or, at least, with the majority of tube amplifiers in high end audio. It's difficult to describe, but the richness embues music with a warm and realness that is intoxicating. The JOR does not do that, it's bass is more lean, and the overall sound of the JOR sounds more midrange centric, while the DA30's center of gravity is lower.
I have not been able to reproduce the perfect midrange of the JOR yet, though rolling the tubes certainly produces great effect on the sound. Again, like the JOR, I think it's the preamp, this time an active one, that exerts itself here. Different 12AU7 tubes lend different sound. So far, Mullard Blackburns sound best to my ear - relaxed, rich, liquid, yet also open, clear, and with good bass. The DA30 does provide excellent midrange and treble, and I can listen all day and night without any fatigue. Initially, I felt I was losing detail or clarity in comparison with the JOR, but more careful scrutiny showed it was giving me all that was in the music, but its more relaxed nature seemed to hide it at first blush.
My DA30 uses the older autobias circuit, which is designed for the larger (6550, KT88, KT90) tubes. The DA50S may be set up for these tubes only as well. Current DA30 and DA60 can also run the 6CA7 and EL34 tubes. I have tried the EL34, and the sound is definitely better to my wife and daughter. I'm not sure, I'll have to try again. Still, as things are with mine, I have been cautioned that tube life will most probably be compromised by me running the smaller tubes in it, though the values of the bias resistors and caps could be increased to let it run EL34 safely (then, I couldn't run the larger tubes...). You should ask Pierre Gabriel (SUPER guy to work with!) for clarification on the DA50S, as this information is outside of my knowledge base at this point.
The JOR I owned was more powerful, and able to play louder. Strange as this will sound, up to the point where things become hectic, the DA30 exerts better control of the loudspeaker. It ultimately produces less power, but up until that point, sounds more authoritative. Both amplifiers ultimately hit their ceilings in terms of power output, but my levels of louds are far louder than most audiophiles. I mean lease breaking levels. In the grand scheme, both will produce enough volume for 95+% of the audiophiles I meet.
As I get a better handle on my DA60, which has just been refreshed by Avi Brand (US Service Rep), I'll be able understand how it sounds in comparison to the others. And, in fact, it may be a better clue in terms of how a JOR compares to a DA30 or DA50S of today. So far, it seems to have more openness than my DA30, a more upfront presentation, and with its behemoth transformers and double the output tube count, as much volume as one wants without running out of steam - the DA60, so far, has not hit a ceiling. I'm curious to see if it actually sounds like a bigger, better, more authoritative JOR. If so, that would give me a better perspective in which to compare the JOR and DA30/DA50S, as I will be returning to the current Jadis house sound.
In the end, as I said, if it is at all a question of value, the JOR is your move. If the cost is not an issue, and you are looking for richer, more liquid sound, the DA50S may be the right choice. They are different flavors, and I can appreciate people preferring one over the other. Avi has obviously come across many, many Jadis owners. He tells me that while the majority of people prefer the more expensive DA30 or DA60, he has definitely encountered people who like the smaller ones better. If this post has tried to get anything across, it's that I can certainly understand exactly what Avi means by that.
GOOD LUCK!!!
Joe