By comparing the sound characteristics of different vacuum tubes, one can determine which tubes are best suited for a particular application or personal preference. This can experimenting with different tubes in the same audio system and listening for differences in sound quality and tonal balance.
| Power rating | Warm | Musical | Detailed | Transparent | Smooth | Dynamic | Powerful | Imaging | Extended highs | Good midrange | Bass response | Score | |
| 71A | 0.7W | ☺ | ☺☺ | ☺ | ☺☺ | ☺ | 7 | ||||||
| 2A3 | 3.5W | ☺ | ☺ | ☺ | ☺ | ☺☺ | 6 | ||||||
| 45 | 3.5W | ☺ | ☺ | ☺ | ☺☺ | ☺ | 6 | ||||||
| 6AQ5 | 4W | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| 50 | 5W | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 6 | |||||
| PX4 | 5W | ☺ | ☺☺ | ☺ | ☺☺ | ☺ | 7 | ||||||
| 10Y | 7.5W | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 6 | |||||
| 300B | 8W | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| EL84 | 10W | ☺☺ | ☺ | ☺ | ☺ | ☺ | 6 | ||||||
| PX25 | 10W | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 6 | |||||
| 6V6 | 14W | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| 6V6GT | 14W | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 6 | |||||
| 300A | 15W | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| 211 | 20W | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 7 | ||||
| 845 | 20W | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 7 | ||||
| 6L6 | 25W | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| EL34 | 25W | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| KT66 | 25W | ☺ | ☺☺ | ☺ | ☺☺ | ☺ | 7 | ||||||
| KT77 | 25W | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| KT88 | 42W | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| KT120 | 60W | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| KT150 | 70W | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| KT170 | 75W | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 6 | |||||
| 833A | 125W | ☺ | ☺ | ☺☺ | ☺ | ☺☺ | ☺ | ☺ | 9 | ||||
| 101D | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 6 | |||||
| 12AU7 | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| 12AX7 | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| 274B | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 8 | |||
| 5AR4 | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 6 | |||||
| 6922 | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| 6DJ8 | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| 6SL7 | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| 6SN7 | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| 6SN7GT | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | 5 | ||||||
| GZ34 | N/A | ☺ | ☺ | ☺ | ☺ | ☺ | ☺ | 6 |
It's important to note that the sound characteristics of each vacuum tube may vary depending on the specific model, circuit design, and application. Additionally, other factors such as power supply, transformers, and speakers can also affect the sound of the amplifier. Therefore, it's always best to experiment and find the best combination of components to achieve the desired sound.
