I'm looking to upgrade the output transformer of a 300B amp and couldn't find any for my requirement. Are there any companies that make custom high quality output transformers that will be a noticeable upgrade to say the woo ones? Am I mad to request this? Primary 2.5K,3.5K,5K Secondary 8Ω, 110Ω 100+mA The Tango XE20S might fit the bill but it doesn't have the high impedance secondary and I've come to appreciate with senns and still on the fence if I should drop it. The different primaries are for me to experiment and hear for myself what impact it has on sound with different biases.