Well, I only got 3 out of 6. However, the other three ended up being 320kbps. So, I feel pretty good about that.
(USB->y2 DAC (Wolfson WM8742) ->PPA headphone amp (B&B OPA627 L/R & OPA637 return signal) ->Grado GS-1000)
Really, though, I had to seriously listen for missing artifacts between the samples, cymbals, harmonics in the strings (piano & orchestra), etc. rather than dig on the groove.
128mp3s do seem to fatigue me more than other bit rates for some reason I cannot find an explanation for. I think most of my stuff is normally ripped in the AAC format. But I have a few albums I ripped at lower bit rates in the less-than-recent past. I notice it sometimes if I mix them with higher quality coding of the same artist. (Zeppelin would be one of those; I have everything ever recorded in digital format but some are 128mp3s and other are WAV. Anything from an AAC and up, I can't tell the difference readily.
Bottom line: I can fit more music on my phone than I could if I had better ears. (I blame seven tours in the infantry over three land wars for that damage! Although, from what my doc tells me, driving with the window down for a year of normal commuting dwarfs most sources of ear damage. I thought it was because I never wore an earplug on my non-firing side.)