I'll add to @djohnson54 comments. I'm an avid tube roller. At one time I was addicted to rolling NOS preamp tubes when I had a SS amp.
Depending on the design of the preamp, rolling in a different brand or style of tube can make a significant difference to the overall sonics of a system. Characteristics such as dynamics, transparency, soundstage can all be affected. Many audioholics change tubes to take the edge off the highs, or conversely to add extension and "air." The caveat is that the amp will play a role in how much of a change in sonics you hear. Your SS amp must be revealing enough to hear the changes from the preamp. But you will hear a difference in preamp SQ or sound signature.
Preamp tubes do last a long time; thousands of hours if purchased from a reputable dealer. A dying tube can become noisy or microphonic. But IME, you can tell when a tube has reached its life expectancy when your music begins to sound dull. There may be less extension, a flat image, or less colour or drive to the music.
I'm a firm believer in having a set of spare tubes on hand. For this reason maybe you should start shopping for a replacement set.
Depending on the design of the preamp, rolling in a different brand or style of tube can make a significant difference to the overall sonics of a system. Characteristics such as dynamics, transparency, soundstage can all be affected. Many audioholics change tubes to take the edge off the highs, or conversely to add extension and "air." The caveat is that the amp will play a role in how much of a change in sonics you hear. Your SS amp must be revealing enough to hear the changes from the preamp. But you will hear a difference in preamp SQ or sound signature.
Preamp tubes do last a long time; thousands of hours if purchased from a reputable dealer. A dying tube can become noisy or microphonic. But IME, you can tell when a tube has reached its life expectancy when your music begins to sound dull. There may be less extension, a flat image, or less colour or drive to the music.
I'm a firm believer in having a set of spare tubes on hand. For this reason maybe you should start shopping for a replacement set.