Impact of using spikes for speakers?

My speakers (Thiel CS 1.2s) have been sitting directly on a hardwood floor which is on a concrete floor in a hi-rise condo. Amplification is Krell 400xi and CD is late 80's NAD.

Thiel sent me a new set of spikes gratis (kudos to them on great customer service) and I bought the Adona floor disks. Spiked them up tonight and have been listening for a few hours.

Can't say that I've noticed any differences (certainly not any material changes). Is there some particular area that should improve by using spikes? I'd be interested to hear others experiences.
Bass is where the biggest improvement is heard. However, since your speakers were previously well anchored to the hard floor, the improvement will be nowhere near as dramatic compared to speakers previously sitting on carpet...Still, a subtle improvement should be heard, as the entire mass of the speaker being exerted on a small surface area of spikes should result in the speaker moving less during the big bass notes. Put on some heavily bassed music and crank it up a bit, you should notice the tighter bass and greater speed. Enjoy!