Grado RS1e vs RS1i vs original RS1 headphones ?

Which one sounds better if any different?
I am well familiar with the newest RS1e but never heard the previous ones.
And another question. Would you recommend Grado headphone amp or something else to go along? For under $500, please, can be used in excellent condition.
This would be for nighttime listening Nakamichi 682ZX deck at moderate level. The Nak does have the amp and output level control. The amp is not too bad, listenable, but not good enough. Still, at this point I am more interested in phones.
I have a pair of RS1's that I always thought were RS1i's...
According to experts on head-fi, the RS1's are best but RS1e's are very good. The Grado amp is fine, but I have had very good results with tube amps using the 5670 tubes. Quinpu
makes the Q-3 amp which sounds great and costs much less than
Douger, thank you. I 'll catch one of them, preferably the original RS1, here or on ebay.