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Battle of 3 single ended high end amp :
Source : AK 120
Amp : from left to right
RSA RS 71 A > RSA Intruder > Pico Power
Headphone : Ultrasone Sig Pro
Cable : oyaide headphone cable
Wagnus mini to mini
RS 71 A :
High : similar to Pico Power , below Intruder
Mid : the sweetest midrange from these 3
Bass : the best bass impact and slam from these 3
Soundstage : very depth , is not as wide as these 2
Separation : the other 2 has better instrument placement .
High : is more open than RS 71 A and Pico Power
Mid : is not as sweet as RS 71 A , is on par with pico power has a bit sibilance
Bass : has less bass impact compare to RS 71 A , is below Pico Power too
Soundstage : wider than RS 71 A , is on par with Pico Power
Separation : better than RS 71 A , is on par with Pico Power.
Pico Power :
High : on par with RS 71 A
Mid : below RS 71 A , is on par with Intruder
Bass : less impact compare RS 71 A , but better than Intruder .
Soundstage : wider than RS 71 A , on par with Intruder .
Separation : is on par with Intruder , better than RS 71 A.
Power wise : RS 71 A > Pico Power > Intruder
Clarity : Intruder > Pico Power > RS 71 A
Mid : RS 71 A > Intruder > Pico Power
Bass impact : RS 71 A > Pico Power > Intruder
These 3 high end portable amp has their strong and weak point .
Nobody is perfect