I can imagine that some headphone amp will sound better with my HE-400 than out of the headphone out of my Sansui AU-7700, but i bet that with these magneplanars or my he 400 this headphone amp WOULD be way costly than my past headphone amp, because this headphone tube amp (very well regarded here) dont compare a second to the Sansui...My few hundred dollars Sansui recap included is so good that i dont wish to pay for a slim upgrade , perhaps one thousand dollars and probably way more for a slim diminishing return...
Buy used and vintage amp, if you use planar headphone and forget any headphone amp around one thousand dollars...Last but not least, the greatest upgrade i ever live to listen, cost a few bucks and transform any sound system to a new level...Almost all hype here is only for selling new gear...I possess now an audiophile system for one thousand dollars, including all pieces, dac, amp, speakers, headphone, bought used or vintage, and modulo some tweaks the resulting system is so good that i have forgot any so called Upgrade for a long time to come...I say all that for the newcomer with few money in his pocket to sparkle some hope for him... inform yourself before spending money