Give you a statement and table with its title in Markdown format, please determine whether the statement is supported or refuted by, or is unrelated to the table. It'a binary classification problem, you should choose the answer between supported and refuted. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| tubes | converter | det / pre - amp | audio amp | rectifier |
| 4 | x | x | x | x |
| 4 | x | x | x | (selenium) |
| 5 (standard) | x | x | x | x |
| 6 | x | x | x | x |
| 6 | x | x | x x (push - pull) | x |
| 8 | x | x x (push - pull) | x x (push - pull) | x |
| 8 | x | x | x x (push - pull) | x |
Title:
none
Statement:
for det / pre - amp of x x (push - pull) the rectifier is (selenium)
Answer:
refuted