How to choose line out transformer?

[karsten21]

Dear wise guys,
I want to drive a line out transformer for 600Ohm load symetrical lines. There are some schematics out at the net but I would like to build "my own" driver stage. It´s more interisting and challenging and I love to learn more about tubes ( It´s a virus.. ) I plane to use different driver stages ( CF, SRPP ... ) to identify which sound would be the best for me. It´s not used for HIFI but for music instruments like Keyboars/Organ/Bass/Guitar/Voice...
As an example to determine a SRPP I need to know the Zload for this stage. Using a 4:1 transformer the load will be approximately 9600Ohms with an 600Ohm load on secondary side. This seemed to me a good value to be used in different driver stages. Higher ratios need to much level at primary side and lower ratio need to less Zout of the driver stage.
One of the challanges is the signal level at primary side. I want to be able to have studio level ( +4dBu ) at the output plus some headroom. If I calculate right, I need for this case a inputlevel of +16dB on primary side.
Unfortunaltely all manufacturers have different descriptions about what is the maximum output level. I stepped through datapages from Lundahl, Sowter and Jensen but in fact I do not know which values are usefull to know to let me choose the right transformer.
Furthermore it´s not fully clear for me what happens if two windings are connected in parallel as an example. If both winding have the same ratio I get the same ration if I only use one winding. But what is the case with the current? It´s dublicated? Does this have any effect if the load will be constant, say 600Ohms?

At least, I have work for my mony ( as the most people of this planet ) for that I have also to take a look to the price which will be increase by tax,shipping,weather,exchange...

It will be great to get some handy tipps or processings how to choose a matching transformer out of the jungle of audio transformers.

Thanks a lot for your help!
Best regards
Karsten