How do I get a speaker with the bass slam of my el cheapo ear buds...?

You know, the ear buds that come free with a Samsung smart phone. Was just listening to Brooks and Dunn’s My Maria over my Galaxy S8 and ear buds, and there is a nice drum track in there and it was nice, deep, slam to it. But if I connect the phone to my stereo system via analog inputs, I don’t get that slam. Do they boost the bass in these ear buds, or is my audio system not delivering the bass as it should?

Oh, and I also connected my phone to my car system via the AUX input and I don't get that kind of bass in the car either.
I'd try something like the Fiio A3 portable headphone amp to see if you like that presentation.  It's only $60 so it's low risk and a reasonable match for what you're trying to do.  You could use it in the house or the car.  

Amazon description:
  • Suitable for headphones ranging from 16 to 150 Ohms. Gain switch for matching output to headphone power needs.
  • Superior sound quality through expertly selected components and design, utilizing OPA1642 preamp and AD8397 amp section.
  • Fully discrete bass boost circuit increases output by 3.5dB at 60Hz, with bypass when off.
  • Handsome all aluminum body and chassis is sturdy and shielding against EM interference.
  • 1400mAh internal battery powers for up to 16 hours of use.

Thank you for your understanding. 
Obviously I got same feeling as you did.
  1. By the way, I tried to connect an iphone 6s to my preamp (using Spotify) and then played a CD via my OPPO, sent to the same preamp. I can hardly think they have overall same sound resulting. It is similar to comparing FM radio with CDs. 
One comment is, if you live in a high cubic volume rectangular room with the correct dimensions for the "slam frequency range" you want, all you need is great speakers driven with enough power. 
BUT... most of us don't... so just buy some $1,000 earphones and enjoy REAL bass with separation only dreamed of by those with speakers.