Please compare MD with alpha primes..
The Alpha Primes are very impressive, more so than Mad Dogs. I prefer AP sound by some margin. Alpha Prime is more detailed, the subtleties in complex music are clearer with AP's, there is more space between the instruments. You feel bass rather than "just" hear it - the lower frequencies are more prominent but not OTT. Alpha Primes give a wider soundstage. AP's are better/sturdier in construction. Better build quality.
Mad Dogs are incredible especially for the price, but Alpha Primes are on a far higher level- they blew me away on first listen and continue to surprise me as I expand my music collection from CD to FLAC and can listen with Fiio X5/Audio-Gd NFB-15 combo. I am delighted that I jumped in and upgraded from MDs for I will not need a new headphone for years-- well maybe until Dan upgrades AP's anyway
Hope this explains in enough detail, I'm still learning about vocab to use!