Would there be any benefit realized if one took a headphone tube amp with preamp outs, and fed it to an integrated amp? My Onkyo amp has the direct source function, and I assume this only bypasses the tone controls, not the amps preamp. Would this then be doubling the preamp? Would this be stupid? Would it be worth it? And if so, does someone here have that perfect headphone amp, with the perfect tubes that might save someone such as myself from excessive experimentation? I hope this isn't one of those already beat to death topics. If so, I'll gladly settle for some links. Thanks.