solo hd is built for portable rig such as ipod/iphone. so actually it doesnot need an amp to push it. else if you want to have a lil change on the sound signature, then you can couple it with an amp. but i doubt you can hear the change of sound signature, because beats solo hd is not made for details/clarity sound sig, just for fun listening.
or... if you want to boost the bass, then amp will help you with bass control.
for me, it is not worth to get an amp for solo hd, because it easily driven by any portable audio player. unless you get audiophile grade headphone to couple the amp.
actually it is not useless. if you want extra bass for ur solo, amp with bass boost can help you to get that.
almost all amp can bass boost such as fiio e11, ordnance, etc... but if you think the bass is enough then just dont waste ur money to get an amp

because it just change lil of the sound sig for solo.
This post has been edited by calmshot: Jul 5 2011, 06:58 PM