I'm in a similar situation of the OP so this thread is helping me out as well. Comparing the A5+ to the P4, will there be a loss of bass with the P4 due to the 1" smaller woofer? Both the D1 and N22 contain headphone amplifiers, is there a reason for that? Which one is better? The A5+ and D1 comes in $50 cheaper but seems like the more powerful and versatile option.