It's not the same thing, but personally , I greatly prefer the sound of my SR80i to that of my HD400.
Hey!, I just had an idea, it turns out that we're both searching for vintage headphones, so I'm willing to search for you're brand and model number, if you'll do the same for me. And I'll PM you if I find anything. Just tell me if you have any special criteria regarding you're HD414.
A few years ago I was lucky enough to score a pair of very rare, limited edition Grado HP1000, they only made 1000 of them, so there's hope for you're HD414.
Oh!, and about two years ago I found out that Joseph Grado had also made an amp to go with the HP1000, it was the HPA-1, of wich they made 150, and the improved and even more rare (50 units only), the HPA-2. .Well a few month ago, a guy that popular headphone enthusiast website, new that I was looking for one and I bought his ULTRA rare HPA-2.
Now, what I'm looking are mint vintage Grado RS1, with the wooden ''button'' in the middle of the grill. Price shouldn't be a problem, so if you see anything, please let me know, but first, let me know if we have a deal.
In case you never came across the Grado HP1000, and it's amp, the HPA-2, I took the liberty fo posting pics, the HP1000 are the ones in the middle.
I should've PM you instead, Oh well!. good luck.