I suppose I should clarify a few things, after some emails I got regarding this thread.
With regard to options: Being audiophiles ourselves, and inveterate tinkers, we know the temptation to look under the hood and see what can be hopped up. That's the sum total of why the option packages exist- we've tried all sorts of tweaks in the amps and preamps over the years and we include them if they have been shown to have merit, unless the tweak compromises reliability. So it comes down to the resistors and capacitors- we figured out which ones work, and those are the options. To date we've not found an example of someone using a different part that outperformed them.
All our products are built with a custom copper wire that is as pure as anything else out there- by rights, we could be cable company :)
With regards to the S-30: Two things need to be considered, actually with any of our amps:
first, they are very revealing (transparent). Please, before deciding that the amp/preamp is at fault (and especially if you use digital as your only source), try a different source! I find that poor digital electronics have glare artifacts to this day and is still one of the reasons I prefer analog. OTOH a good digital system can be listened to all day, but what is a good system and what will have glare is not all that predictable- certainly price has nothing to do with it... and often what others say about it or what your own experience has been with a less transparent amp/preamp could well be irrelevant. I don't mean to insult anyone, this is just my experience over the years (FWIW, overall the amps lack a reputation for glare amongst our customers- that phenomena is always symptomatic of one of these two issues I bringing up here).
Second: Duke and others are quite right: the amp/speaker interface is **crucial** (see
http://www.atma-sphere.com/papers/paradigm_paper2.htmlfor why. Please note that the paper is not talking specifically about our products, although they do fall into one of the two categories discussed. The S-30 is one of the smaller OTLs made and runs very little feedback (a simple way to increase the feedback is to run the unit single ended, without the shorting jumper in the XLR connector; if the amp seems to sound better, then the impedance curve of the speaker is an issue- and can well be solved by use of a set of ZEROs.), consequently it is 'load sensitive' in the same way some of Nelson Pass' 'current source' amplifiers are. If the 'glare' is at a certain frequency (for example at the crossover), a simple Zobel network can be devised to correct the matter. The S-30 is a special case in that it makes more power at higher impedances, this causes some modern speaker crossovers to not work in the way that the speaker designer intended if they are used to Voltage Paradigm rules!