My guess is that the speakers, more than anything else, are the culprit. I've heard a number of single driver speakers. I love the detail, clarity and liveliness (incredible dynamics within a somewhat restricted absolute volume), but, they tend to favor smaller instrumental groups, vocals and jazz. Anything that requires a really wide frequency response (particularly deep bass) and weight and power (orchestral music and rock music) does not fair as well, regardless of the absolute volume.
Have you tried these speakers with other amps that have enough power to rule out clipping as either a contributor or the cause of the sound you are hearing with rock music? The sound you described could be symptomatic of an amplifier reaching its limits. Single ended triode often can becomed strained and sound as you described without producing the obviously harsh sounds of hard clipping.
I run 6 watt/channel amps with 99 db/w efficient speakers. I hardly ever hear really obvious signs of strain with rock music. What really taxes my amps is choral music, particularly, choral music without instrumental accompaniment. At what seems to be somewhat low volume, I can hear the sound become murky.
Have you tried these speakers with other amps that have enough power to rule out clipping as either a contributor or the cause of the sound you are hearing with rock music? The sound you described could be symptomatic of an amplifier reaching its limits. Single ended triode often can becomed strained and sound as you described without producing the obviously harsh sounds of hard clipping.
I run 6 watt/channel amps with 99 db/w efficient speakers. I hardly ever hear really obvious signs of strain with rock music. What really taxes my amps is choral music, particularly, choral music without instrumental accompaniment. At what seems to be somewhat low volume, I can hear the sound become murky.