I've looked at discussions comparing these on this and other forums, but I'm still trying to decide which to buy. I know that both of these get good reviews and recommendations. It seems about equal between them.
 
I bought a Clip+ about 2-1/2 years ago. It is Rockboxed with the latest FW (02/07/2015). I'm considering getting a 2nd one while they are still available in case this one dies. The other thing I'm considering is just waiting and getting a X1 if my Clip+ dies and new ones are not available. Perhaps even getting a X1 in the near future and using the Clip+ with the HF5. I listen to mostly classical, jazz and new age. I listen to the following headphones.
 
With Clip+
Ety HF5
Sennheiser HD 25-1
Sennheiser HD 380 PRO
Sennheiser HD 590 with PA2V2 added.
 
With HeadAmp GS-1 or Gilmore Lite
Beyerdynamic DT880-250 (old flat grill version)
 
I'm happy with the Clip+ and the other equipment that I have. I'm almost 70 YO, but my hearing is somewhat better than most men my age. I can clearly hear 10kHz, can hear 11kHz somewhat well and can barely hear 11.5kHZ. These are at levels slightly below what I normally listen at and using the Senn HD 25-1 without any treble boost.
 
Any recommendations would be appreciated.

I think in your situation I would go ahead with X1 taking advantage of the line out for amping your full-size headphones. X1 does perform better than a Clip by default from its headphone out, (and when amped) also has more power. Although the UI isn't quite on the level of an Apple device its quite usable. In your situation, I would keep the Clip with your HF5 (as you suggested) purchase an X1 and make a dap/amp rig. For the $100 X1 costs it offers a lot of features and sounds pretty good. Why not treat yourself to a new toy. You won't see many people complain about X1 because its so cheap yet full of features.

With the X1, I doubt that I would need any additional amplification for any of my headphones except possibly the DT880.  However, I have no intention of using the DT880 with anything except a CD player and HeadAmp headphone amp. Part of the reason for this is that the cable is not removable, so I can't change to a shorter cable. That makes it too cumbersome for portable use. For the same price, I could either get the X1 or a 2nd Clip+ and an E11K. The X1 alone does make sense as it's a single unit and neater.

needmoretoys said:

With the X1, I doubt that I would need any additional amplification for any of my headphones except possibly the DT880.  However, I have no intention of using the DT880 with anything except a CD player and HeadAmp headphone amp. Part of the reason for this is that the cable is not removable, so I can't change to a shorter cable. That makes it too cumbersome for portable use. For the same price, I could either get the X1 or a 2nd Clip+ and an E11K. The X1 alone does make sense as it's a single unit and neater.

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That's correct, for everything besides your DT880 - X1 would do well enough, some of us are extracting better performance from line out with our own amps. (so that option is always there too) . Regardless of this I think your headphones have more potential than a Sansa unit offers. (and I do like the clips).

Well, actually considering the price of the clip, there's no reason that I couldn't afford to get both. I'm in the process of checking the condition of my Clip+ battery to see how long it will play on a charge. If it's been degraded much over the past 2-1/2 years then I might get another Clip+. If it's still good then I will likely move the X1 from the saved area on Amazon to the cart and buy it.