Harsh on tubes?

the circuit drives the tubes at their operating max shortening their useful life.
Larry

I think the word used here should be hard on tubes, not harsh on tubes. Yes, some preamps put a tough load on their tubes, which means that these tubes will have a shorter lifespan than normal.
Should you avoid them? That's up to you. Some of the finest sounding tube preamps for the money are hard on tubes. If you want piece of mind over and above sonics, then perhaps it is best that you avoid such preamps though.

Cheers,
John

Some designs run the tubes hard which can shorten their life.

If tubes are run hard (high current through the tube and/or high plate voltage) they tend to have a short life. Run them conservatively and some tubes have an incredibly long life. There are people who report that their table radios have been on for most of the day for 50 years with the original tubes.

Small signal tubes used in preamps typically last much longer than output tubes in amplifiers. But, some designs do run them hard so the tubes may last only a year in daily use. The good news is that when they go, you just have to replace the tube; there is far less chance of small signal tube failure causing damage to the component than is the case with power output tubes in an amplifier.

Whether you can live with an preamp that runs tubes hard depends on your own willingness to provide maintenance, whether you are uncomfortable with the fact that the tube and sound may be deteriorating quite quickly and you have to monitor the situation, whether the cost of retubing the preamp is reasonable to you, and whether the sound of the particular model warrants the extra cost/trouble.