You'll be fine on most recordings with 34 watts, but not on some recordings. And I suspect that a major reason for the diversity of opinion in the previous responses is that people listen to different kinds of music.
Given that your listening is at "low to moderate" levels, the most significant variable is likely to be the DIFFERENCE in volume between the loudest notes and the average notes on the recording. Some well engineered classical recordings which use minimal or no compression will have a ratio of peak to average volumes in the vicinity of 30 db, which means that 1,000 times as much power will be required for brief volume peaks as for the average volume level of the recording.
Most rock recordings, on the other hand, are compressed such that less than 10 times as much power is required for volume peaks as for the average volume level of the recording.
Neglecting room reflections, it can be calculated that at a centered listening position 10 feet from the speakers 34 watts into your 89 db speakers will produce a sound pressure level (SPL) of about 100 db, assuming the specs are accurate. Averaged over a broader set of positions, but at that same 10 foot distance, the corresponding figure is 97 db. "Moderate volume" probably means an average SPL in the area of 70 to 80 db. Many of the symphonic classical recordings in my collection that are especially well engineered, meaning in particular that they are minimally compressed, will reach SPLs of 100 to 105 db at my listening position on brief volume peaks, when played at that kind of average level.
Finally, it appears that although your speakers are nominally rated at 8 ohms, they reach a minimum impedance of 4.1 ohms at some frequencies. That will further reduce your chances of success with a marginally powered tube amp.
Hope that helps. Regards,
-- Al
