with some passive crossovers as put in multidriver iems, going balanced can alter the tonal balance somewhat, because the load impedance (headphones) is driven by 2 parallel amplifiers with the load seen in series. for jh13 i dont find it detrimental, just the usual deepening of bass response and increase in slam and transparency, but conceivably on yours the mids may be slightly effected, either that or you just arent yet used to the increased bass response and the mids therefor seem recessed by comparison. just a couple of other possibilities other than opamp preference.
@ Nigel: no problem man, all true, I know estreeter is partial to the transportable in the right situation, so thought he should know it wasnt a blind or uninformed choice on your part.
re 1611/41 yeah thats where my preference for 1641 came from too, fiQ, possibly i would prefer 1611 in the dba2 as well, who knows, but i doubt it would displace the lme49990 its my new single opamp poster child. doesnt see much airtime except in 'the wire' home amp these days though, i'm fully differential chips all the way portable these days, rocking opa1632dgn at the moment, love it, yet another jhet input, gonna graft in some lme49610 buffers one of these days and see how badly battery life is effected.
