Jeff1,

 I would have had the same issue not that long ago about bass and other issues as well. I couldn't believe how much headphones have improved over the years. I own a few sets of phones, so that may well tell you how my opinion has changed. So far, I have: Hi-Fi Man HD400S planar phones; Great and accurate bass, to my surprise, and much more...... ZMF ORI planar phones as sold by Decware; Probably my favorites in most ways, including that deep bass that you ask for...... Sennheiser Momentum 2.0 dynamic phones; Wonderful if you don't like cords, but no match for the first two. Having said that, they also have decent bass, if not on par with the first two phones...... Grado SR225i dynamic phones. A bit bright for my taste, yet, marry well with certain amps.
So, I bring up amps.... Yes I do for a very good reason. The re is NO small difference between each amp that I own and it's marriage with the phones described. Oh boy, here we go. My favorite amp is a headphone amp design by John Broskie. It is built up with a tremendous power supply, some fairly rare automotive radio tubes, used as radio frequency oscillators, and uses an output device that is normally used as a voltage regulator. The result is nothing that I have ever heard before in a headphone amp. Slam is the biggest, but not the most important word. Bass control, midrange accuracy, and a not too in your face treble, make it unbeatable. Next is the Decware rachel amp that is normally used for speakers, but also sounds incredibly musical with phones. Of course, there is my Xenos SS headphone amp that holds it's own in it's category. Good for the Grados.  Lastly, I have DAC/Head amp by Xian Sheng that is heavily modified. Great DAC, not bad for a SS amp either. So the story could well continue on, but you can now see that all of this equipment was bought and kept ON PURPOSE, in some preference to speakers and the room acoustics involved. More later, less sooner.

The ORI phones are a different animal than the Grado phones. The only reason that I would say that each has it's purpose is because of the possible arrangement with a certain headphone system. So, that means that the Grados are often relegated to SS amps, or in the shop for troubleshooting a problem. The ORI phones are in a completely different category for serious listening through my Aikido tube amp.
The difference in sound and presentation is that the Grados are much brighter and more sensitive. They have good bass and good midrange as well. Their presentation is much more forward sounding than the ORI phones. The ORI phones, when played through either the Decware Rachel, or the Aikido  amp have richness and more layed back presentation of the music. Bass is quite impactful, but also very deep. treble is less forward and yet quite detailed. Don't forget that I also own a set of Hi-Fi Man HD400S phones that are also planar type. They give yet another presentation of the music, and so, it can become a choice of whether I want to listen to a certain recording this way or the other.

Hi Jeff, I also had a very similar issue. However, I took a break from headphones for a couple of years and when I came back, I was floored by how the low-end was with my digital piano.

Here is a resource I found that really helped me with learning more about headphones.

https://keyboardkraze.com/best-digital-piano-headphones/

OK, let me throw my two cents in.
First off, for me, forget the digital ( and I've had very close to SOTA stuff ). Only analog for me. Life is short and only so much time to listen. ( plus I've got a record collection Mikey Fremer would cut off his right arm for ).

Turntable:  Amazon Grand Referenze ( so no slouch )
Arm : ( Pete Riggle Woody ) preferred over a Moerch DP8 and a Fidelity Research FR66S.
MM cartridge ( AT 150MLX or Shure VIII w/ Jico SAS stylus) only feeding the Decware ZP3 ( modified by Steve )
then into an Intact Audio 47 step silver audioformer , feeding  into an 2005 era CS84 I bought from Parts Connexion ( to be modded soon )
A DIY speaker to headphone connector feeding the cans I have used with this set up. ( Senn  HD650 w/ Cardas Cable, AKG 701 (,Austrian version, AKG 702 w/ Cardas Cable- Austrian version ).

The point of all this rambling.

Listening set-up is no slouch.

It took me a while to figure out grounding issues and I had noise ( hum).
But once figured out, the ZP3 into the Decware SE84CS is so quiet as to be unbelievable into my cans.
Listening now to this set-up into Grado GS3000e cans. WOW!

And I'm favoring this over Stax  cans ( SR007MKll and SR Omega ) fed via WOO AUDIO WES with upgraded tubes ).

What can I say. My headphone set-up is , while not dead quiet, very close to it.

In my case, didn't need any resitor network.

Of course, YMMV.

Happy listening,            Crazy Bill

P.S.   Glad to hear this set-up worked for you. Enjoy the music.

So far after about 8 months of headphone listening I can say there is a miss of that impactful body feeling of having speakers and a sub. Although my previous speakers were Legacy Signature SE and Metro sub my set now is much more revealing specifically in the mid and mid bass area. Lower end bass is pleasingly good. Better on some discs lacking on others but I attribute that to better revelation of the mastering.

My bass reference has been the Beatles Come Together. A nice prominent melodic bass line. To me just as enjoyable with my set now with added resolution in the rest of the audio spectrum.

I suppose the speaker vs headphone and analog vs digital etc debate just comes down to personal preference of the listeners ears. Each way of listening has positives. I can say that the headphones have released me from the acoustic room treatment rabbit hole and the chase for minute changes which can detract from just the pleasure of listening. Getting older could be it as well. As a life long hobby/pursuit transitions your personal philosophy and definition of enjoyment.  

To answer my own question. A good headphone set up can definitely provide a low end level of reproduction and clarity. No body feeling of sound pressure obviously so in the end preference is a personal choice.