Confused. Need VERY sensitive headphones.

So, this might be a BORING THREAD!! SORRY!! Just trying to solve, what I thought would be a SIMPLE problem. Not so much.....

I JUST need a portable headphone amp, ideally with a DAC, to bypass the ancient 1-bit DAC, in my 30 year old SONY D-EJ1000 Diskman CD player I LOVE! (Fuzztone thinks I’m bonkers!), (It’s NOSTALGIA dude!), utilizing the 3.5mm jack sized line-out, that’s both optical and regular. Pretty cool to have a TRUE optical line-out-in, on a 30 y.o. Diskman!! And it WORKS perfectly!! Have used it as a transport in my home system because it runs on batteries (no AC voltage pollution), genus huh? With a NICE Macintosh amp, Arcam DAC, and B&W 805 speakers on stands, sounds WONDERFUL!!  Friends see it, can’t believe it!!   The problem I’m running into, is these “portable amps-w-DAC” use either: an iPhone lightening jack(Built for iPhone) or, a mini USB(Android?), or strangely, RCA jacks. What is this so bloody hard to find?? And a lot are EXPENSIVE! $500.-$1000.00+ for a portable headphone amp/DAC?? Seriously? Some even have TUBES!! Crazy!! If you put it in your back pocket, and sit, CRUSH! There goes your TUBE!! How bizarre!! Tube/s in a “PORTABLE“ headphone amp?? I’ve NOW seen it all!!!

I KNOW this post isn’t: sexy, very interesting, DEFINITELY not informative!! Maybe the fact a 30 y.o. SONY Diskman HAS an optical line-out, and makes a GREAT CD transport IS informative to somebody (LOL!). I’m JUST trying to solve a MINOR problem. Sorry all!! TRULY!! If I made you laugh, GREAT! Looking at you Fuzztone! 😊😊😊
I’m about to give up. 😖😖😖

Okay, so now I’m looking for a portable headphone amp for my portable CD player/iPods/iPhone, that has these 3 requirements:

1) An optical line-in input jack would be great! Regular line-in jack okay. Really only the CD player TRULY NEEDS this amp. The DAC upgrade would be just a bonus for the iPods and iPhone.
2) A good quality DAC, to bypass the DAC in the SONY D-EJ1000 Diskman.

3) Introducing no “hiss” in the background from the amp. That would be a deal killer.

Any suggestions?? I looked at Moon Audio’s Mojo, $500.00! And no optical input. Has very good reviews, but EXPENSIVE! And I CANNOT find the brand of DAC they use. I REALLY like Wolfson DAC’s, not a huge fan of Cirrus DACS, Apple uses Cirrus DAC’s in their current iPods, and iPhones. Apple used Wolfson DAC’s in early iPods. People rave about the sound of the Wolfson DAC iPods. Although I’ve heard higher-end Cirrus DAC’s do sound good. Not aware of other names of quality DAC’s, I’m sure there are some. 

And, if possible, around $200.00?? Maybe a little more, but $500.00 is too much for me.
Thank you all for your HELP!!!! 😃😃😃😃

Fuzztone,
               It’s cool, it works, it’s from my “happy time” past. I love it, just as I LOVED my 1968 FIAT Spyder until a very old guy totaled it running thru a red light and crashing into me!!! Was SO mad!! All I have left of it is the wooden and aluminum Nardi steering wheel, the same steering wheel in vintage 60’s Ferrari’s. Has three polished aluminum spokes with slits cut in them, thin wooden rim. Anyway, the point is, it’s portable, I do own iPods and an iPhone as well, but this CD player is special. It’s the best CD Diskman SONY ever made. All magnesium construction, a true optical line-out, 100+ hour battery life, light as hell, lighter than my iPod Classic160 gig. Thin and sexy! And a really cool blue-backlit remote and a nice charging stand. It’s “NOSTALGIA”.
Does that answer your question fuzztone?? Do you have anything from your past you cherish? No idea how old you are. I’m 52. I think a 30 year old, SONY CD Diskman that’s still working is incredible!!That being the issue, totally weak headphone jack output, I’m going to go all in. I’m going to buy a portable amp with a better DAC, than the 1-bit DAC SONY put in there. I assume it’s a SONY DAC, not a Wolffson DAC. Use the line-out to bypass the SONY DAC. Better DAC, portable amp, I’m happy!! I think. Worth a try. I’m not joking, this silver sliver of a CD player makes a hell of a transport in my home system, it would truly amaze you! And because it runs on batteries, no coloration from AC power. It works REALLY well!! Use an AudioQuest Forest optical line-out cable.
Thank you all for your input!!! I’m sad there are no real headphone only solutions, one of you suggested the original headphones, but I threw them away as they sounded awful. But maybe this will be better because I can bypass the OEM DAC with a current, really good one, as well as amplification!

Of course if you are set on portable please justify a 20th century portable CD player in the 21st century.

Portability - settle for the orig headset.  It's pretty decent. If you want upgraded headphones you NEED an amp period.
The FiiO A3 is only $58 & 3.25 ounces.

The choice you need to take is the one you don't want.

Get a Fiio headphone amp.

Also, I’m not adverse to buying in-ear headphones, but honestly would prefer over the ear headphones, if any can be driven by my CD player.
   Back in 1990 it costs me $200.00!! I actually have two of them, one I gave to my dad, who never used it, and he gave it back to me. Thanks dad!!😃😃

Thanks again,
                      David J.