If you want volume, you should be looking for speakers with a higher sensitivity than the Thiel's which is 87db. Since a 3db increase in sensitivity is the same as doubling amplifier power, a speaker with 93db sensitivity and your amp would be like using a 600w amp on the Thiel's. Look here,
The Tyler Pro Dynamics series are high sensitivity, but their other speakers and the Brystons are about the same sensitivity as your Thiel's. Considering that you want volume and using the calculations here,
an 87db speaker may need as much as 1000 watts on peaks to meet your needs, however a 97db speaker would only need 100 watts. Trying to get volume from a lower sensitivity speaker, it is more likely that the amplifier clips on peaks, causing the distortion.
Take a look at Zu Audio and their liberal return policy,
I have listened to various Zu speakers, and they will definitely rock, but can also do other music well.