Tube Amps vs Solid State vs Modeling

Technology: Uses glass vacuum tubes and heavy output transformers to drive sound.

Sound: Offers rich warmth, natural harmonic bloom, and smooth distortion when turned up.

Cost: The most expensive of the three types of amps.

Weight: Generally quite heavy.

Failure Mode: Usually start to have issues slowly, giving the owner time to get repairs before a catastrophic failure.

Maintenance: Have the longest parts support of all three types of amps.   Amps from the 1950s are still being repaired today.
Easier for do-it-yourself repair, although caution must be exercised because of stored high voltage.

Downsides: Heavy to carry, requires expensive tube replacements on a regular basic, and needs careful maintenance.

Technology: Uses hard-wired transistors and analog circuits without vacuum tubes.

Sound: Delivers clear, consistent tones that stay clean even at high volumes.   Good for jazz and country.   Bad for rock and blues.

Cost: The least expensive of the three types of amps.

Weight: Much lighter than tube amps, making transport easier.

Failure Mode: Usually instantaneous and without any warning.    Catastrophic in many cases (shorted output transistors, creating
burnt circuit boards and smoke).

Maintenance: Require infrequent regular maintenance - occasional potentiometer cleaning if they become scratchy.

Downsides: Lacks the organic warmth and dynamic feel of a real tube power section.   Manufacturers tend not to support
solid-state amps with parts much beyond the era of the amp, so parts can be hard to find.   More difficult to service than tube
amps, usually requiring a professional technician.  

Technology: Uses digital computers to recreate an entire signal chain, including cabinets and microphones.

Sound: Extremely versatile with hundreds of built-in amp styles and effects.

Weight: Much lighter than tube amps, making transport easier.

Failure Mode: Usually instantaneous and without any warning.  Catastrophic in many cases (shorted output transistors, creating
burnt circuit boards and smoke).

Maintenance: No regular maintenance.

Advantage: Great for solo performers- versatile sounds in a small package.   Eliminate the need for effects pedals.

Downsides: Parts can become obsolete rather quickly.   Like solid-state amps, manufacturers do not support these with parts
beyond the era of manufacturing, so they can become non-serviceable within 5-7 years of purchase.   Require professional technicians
for service.    Often considered "toys" by established bands, so not usually seen on stage in backlines.