Upgrade path

It’s a good thing that different recordings sound different. You’re hearing what’s on the recording instead of a coloration imposed by your gear. A coloration may sound good at first but eventually you will notice that you’re missing things that come with uncolored sound.

I’d say stay with what you have in that area and I agree that you should get a sub or two if you want more bass. I don’t think you’ll get there with a different amp.

2channel,

Here are the specs for your speakers.

Sensitivity: 91dB/W/m. Impedance: nominal 5 ohms, minimum 3.0 ohms, maximum 7.5 ohms including bass resonance. Power handling: peak 250W for 10ms, average (pink noise) 25W. Recommended amplifier power: minimum 100W into 8 ohms.

With a high sensitivity, benign impedance curve and reviews stating that Theta doubles power to 400 wpc into 4 ohms, 200 watts should play them loud enough to drive you out of the room before clipping. Some people feel that you need a more powerful amp to properly control the bass cones. A more powerful amp may get you better bass, I don’t know, but a sub will definitely give you deeper bass and take some of the work from the Dunlavy’s bass cones allowing them to distort less.

There are a lot of nice amps out there and I’d bet you could find one that improves on your Theta. Maybe you should talk to the people at Theta and see if they can upgrade yours and what it would cost.

2channel, Good luck with whatever direction your audio journey takes you.  There's certainly no shortage of options out there.