I would say yes, there is a significant difference. I was not blown away , when I first heard it, but I did think it was better than the LD1+. Now that I have heard it more, I think it is safe to say that I am blown away.....I love it!
For me, I seem to need awhile with my cans and amps to really let it sink in and to adjust to the difference ....it takes me awhile to really soak it all in.
I feel pretty much the way that most people explained the RS1i & MAD EAR combo to me.....it just sounds magical....great synergy, indeed. Guitars have never, ever, ever sounded better
I have not listened to my LD1+ since I have received this amp.
I will say that I did plug my AKG Q701 into the MAD EAR today, and they sounded nice, but the same magic does not exist as with the RS1i. It does not even compare, IMHO.
I can't say whether the MAD EAR +HD is worth the six or seven times the cost of the LD1+.....but it is significantly better.
I really can not imagine anybody owning and RS1 not really enjoying what they would hear from this amp.
I can feel your anticipation and I can not wait for you to post pics and to hear your impressions.
I think I can honestly say, that if I had to live with this combo from now until doomsday....that I would be very happy.
I may add the PS500 at some point to my RS1i and Q701.....but I don't see this amp going anywhere!