This tube amp is one the most popular tube amps created by chinese "Veteran", amp serie brand is "Rivals", company is "Himing", its EL34 tube amp has been sold more than few thousand copies! this is 2nd kt88 mature treasure version tube amp. it's used for 10-150w HIFI Speakers for all music type also for high dynimic music.
Standard with tube option is the version without bluetooth but with all tubes Standard without tube option is the version without bluetooth, without any tube(no tube) Bluetooth with tube option is with bleutooth function and with all tubes Bluetooth without tube option is with bleutooth function and it's without any tube(no tube)
Upgrade 5z3pa rectifier option is upgrade the default 5z2p rectifier tube to shuguang 5Z3PAT tubeWith all tube option is with all tube and with 5z2p default rectifierWithout any tube option is witout any tube But the tree option is always include bluetooth module