1st: How much does the amplifier that is powering a transformer change the sound of the earphones. I have been assuming that if I powered the SRD-4 with a solid state that it would sound different.
if it changes the sound and I preferred tubes, would it be better to buy a stax amp with tubes or a tubed or hybrid amp to power an energizer.
2nd: If I bought an amp, would a balanced cd or dac source sound better than single-ended. Are there gains similiar to what is claimed for balanced dynamic phones?
I listened a lot more to the SR34 set today and the longer I listened the better it sounded. I am set up so that the stax, powered by a hybrid amp and my senns powered by a Meier Opera are both on, and I can switch between them. After listening to the stax for an hour or so, I switched, and the Opera-equimox-senns combination which is my "best sound I ever had' seemed dark and a bit veiled, yet offered some soundstage and air that the stax didn't. Onward and inward.
1) The sound of the SR-30's, when driven by the SRD-4, does indeed change based upon your amp. IIRC of my experiences more current = better bottom end and greater warmth all around. I never tried tube versus SS on a SRD-4 but I would assume some level of change should be noticeable; I usually preferred the sound of the SR-34 system with a British / American SS amps of the era versus most of the Japanese sound. For example, my demo display system constantly changed but the system I remember being quite fond of was when we used the (original) Mission Cyrus 1 (http://www.zenn.com.sg/Cyrus_1a.JPG) amp w/booster power supply system to drive the cans - a very decent sound.
2) OK, we / you / I am going to open up a can of worms thanks to that question and my (following) big-mouthed answer So, here it goes:
I would say not to fixate on such matters at this level: as nice as the SR-34 is as the price level there is no reason to overkill the thing with a system tweaked out to 3 times it's potential performance level. Single ended would do just fine. I would say that DAC chip is MUCH more important with Stax than worrying about balanced or single-ended - do NOT go with a Sigma-Delta (1 bit) DAC / player if you expect your current/future Stax system to sound anywhere near what you hope it to be.
You see, things are different in Staxland. Over the past 20 years, thanks to the advent of digital, people have been focusing more and more (they believe) in attempting to get the most detail out of the source and into the speaker. Enhanced DAC performance, greater amplifier detail and clarity, enhanced preamp transparency, etc. are common audio development targets / marketing copy. But, believe it or not, to counter this in comparision to speakers of 20 years ago, today's transducers (both speakers and headphones) are more commonly a bit warmer in sound character than they used to be. Read: many of today's speakers/cans have more bass than before, IMHO to better balance off the more emphasized top end response of all but the highest-end electronics. You have personally seen this in the Sennheiser sound and their incredible market penetration and popularity: the cans sound goes very well with the [common] sound of the [normally used] electronics they get hooked up to.
Stax designs go back to an era when speakers were a much weaker link than they are today, and when electronics simply weren't as good either. This is just my opinion, but the Stax cans extract a lot of detail from just about any source. So hooked up to a source with a very lush, analog-type "classic" balance...and they sound simply fantastic. Hook up Stax to a system balanced to the modern paradigm of super-high resolution at all costs...and they sound, ummm..."off". They simply don't like that input and, IMHO again, seem to present "too much" to the listener with a disjointed presentation instead of a harmonious whole.
So, when you design your system around Stax, you MUST go for the SYNERGY of the entire system, not just single pieces picked upon their own individual performances. In the case of the DAC/CD, you must go for "musicality" first and not necessarily worry about "detail", "bass response", "SNR" and most of the other common audiophile questions that get bandied about prior to the purchase of most equipment. A synergetic "musical whole" is much more important with a Stax system than simply getting the "best" in one area while, somehow, sacrificing the balance or performance of the sound someplace else. IMHO the Stax cans will make up quite a bit of the difference in (any) reduction in detail or transparency with their own natural detail extraction abilities (because you DON'T want to hear a Stax system with a poorly balanced system that has not been designed for overall musicality above specs: it simply yells at you and I believe this is why some people who try Stax for a short-term experiment are unsatisfied).
Pick a CD deck and complete system that sounds good, usually the deck is based upon PCM-63 and it's children, rather than fixate on technical details like single- or double-ended.
To my ears, when I listened to the Senn 650's driven by a maxed-out HeadRoom Max amp, it did sound darker than the Stax sound that I was used to. Not much, but it was somewhat darker. The Stax sound is more upfront, sometimes a bit in-your-face depending upon both your system and the Stax models in question. That's the Stax house sound, like it or leave it for most people. While most systems put you in, say, 3rd-row seating for the musical performance Stax places you in the !@$# orchestra pit, touching shoulders with the musicians. It is a taste and sound not to the universal acceptance. A trumpet's high notes played close and live can be almost painful and I like that experience recreated, while others prefer being just a bit further back when Johnny blows that note. Different strokes for different folks, rather like asking for the universally preferred seat at the movies: it simply doesn't exist. As I stated, the SR-30's have a midrange that is more open than most cans in it's (then new) price range, but it did have to give up something, right? They weren't exactly the best imaging cans in the land and a great part of that is the fact that they are supra-aural; they can only do so much with the format at hand.