I've lost my bass....

Try listening with your back right up against the wall - the bass is usually stronger near room boundaries. If that doesn't work or if it's impractical, then Newbee's suggestion is probably the most effective solution.

You do not mention how far into the room the speakers are placed.

As mentioned above, positioning the speakers closer to the wall they back up to will allow the room itself to reinforce the bass response. But too close and things start to get muddy-sounding, as all speakers have different room interaction characteristics, so experimentation is your only option.

Heck, your listening position may actually be in a bass node itself - mine was, and I had to rearrange my entire great room (30'x20'x15' vaulted) to get out of the hole. I only found this out after spending big bucks replacing alot of gear, when my dealer measured my room response with a Real Time Analyzer (RTA). Taking full advantage of the room's shape and features in the best configuration made the single-biggest change in sound quality my system has experienced (and it was FREE!).

Also, Room Treatments CAN significantly affect bass response if you can figure out where to place the treatments to even-out the room modes, nodes and lull-points.

Rives.com and MichaelGreenAudio.com (among others) can help educate you on these principles. This is truly the 'black art' of the audiophile biz...and the only way to get the most out of the equipment that you have.

Hope that helps - good luck finding your bass....

There are some good suggestions by all above. Newbee is correct about playing with the speaker and listening chair placement. The closer to the wall the more the back wall will influence (good or bad) the bass regions.

I'm not that familiar with different tubes or tube amps but I believe there are very few amps that can really achieve that absolute control and visceral punch in the lowest octaves.

However, it seems that you had some of this before, and now it appears to be gone. I do believe that a certain amount of room pressurization helps. The fact that you now have a more open L-shaped room probably does not help matters.

Bottom line is no two rooms are exactly alike acoustically. But there are usually several ways to influence sonics one way or the other.

Does the new room have as good or thicker carpeting as the previous? Also, depending on ceiling height and reflection, your bass sound waves may be collecting and become trapped in the upper corners where the back wall meets the ceiling.

-IMO

I disagree that changing amps will not affect the quantity of bass and there are several reasons why i believe this. The two reasons listed below basically sum up all the various reasons that may fall into multiple different categories though.

1) Various amps are of different circuitry from one another

2) Various amps don't respond the same to various loads / impedances

As such, not only can the solidity, impact, control, definition, etc... of the bass be altered when changing amps, so can the quantity. While i don't think that this is your main problem ( probably room acoustics ), i did want to point out that it is quite possible that changing amps could provide you with a very different sonic presentation over the entire frequency range. Sean
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adding active sub may be even more pricewise beneficial than changing amp.