03-14-10: Narrod
60 watts of tubes will do ok except for the bass unless that amp has a good amount of current. Otherwise, it will be uncontrolled, flabby and without any real slam.
I disagree. From my experience and research, bass control and tonal balance is primarily a function of the speaker's impedance curve. With a 6 ohm nominal and 4 ohm minimum specification, I think bass quality from a push-pull tube amp with 4 ohm taps will be a non-issue. An OTL or SET amp will be another issue, however.
The issue with these 87dB speakers and a 60wpc amplifier of any topology, is overall volume and available headroom for dynamic peaks.