Can you ever have too powerful amp for speakers?

NOPE if it is a good one.

The volume control position also depends on the source, my phono settings are considerably higher than ones for CD.

The gain of an amp does not change. It will amplify the signal exactly the same regardless of the level of the signal, or it will try to. So an amp rated 200 WPC into 8 resistive ohms, with an input sensitivity of say 1 volt would give an output voltage of square root of 200 times 8 or 40 volts. However, into an 8 ohm resistive load, this also translates into a current of square root of 200 divided by 8 or 5 amps. However, peak current implies multiplying this by square root of 2 or 7.0711 amps per channel. So, if the speaker can handle forty volts and 7.07 amps, then we are good. But, it also comes down to movement of air. The signal coming from the amp to the speaker is translated into the movement of air to make sound. Therefore, for conventional speakers with cones, the cones actually move at a particular frequency, move air and thus makes sound. Trying to force a speaker cone to move too far or too fast or putting too much current or voltage through or across the speaker is what makes it break or fry. All that said, if you have a volume control on your pre-amp, just keep it down to respectful levels and the speaker would never get close to seeing 200 watts. Unless it shorts, then you have a very different problem. Seriously, most listeners would get blown out of the room at 20 WPC of clean signal and amplification. If you have meters on your equipment, you can see, you rarely if ever get max output power from the amp. Not even close. Especially if your pre-amp's volume control is cranked down. One needs powerful amps for dynamics and especially for difficult speaker loads. That is why efficient horn speakers don't really need much power to drive them.

I may have gotten peak current/voltage mixed up, (it's been awhile), don't have a cow, the result is the same.

I hope this helps.

Enjoy