Switched head unit. Do I really need an adapter?

[chiefFX4]

I just went from one of the first satellite ready Sony head units to a brand new Panasonic head unit. The tuner I have is one of the first types that came out so its universal and the same plug is on both ends of the cable that came with it. It says I need adapter CA-PANSC1U to run the sirius to the head unit. The cheapest the adapter can be found (shipped to my door) is 40 USD. If I were to buy a brand new tuner then all that comes with is the tuner and the correct cable. What I'm trying to figure out is why do I need a powered adapter to make things work. Everything I've found says the adapter powers the tuner as well. Why can't I just find a cable that has the right connectors on both ends and plug that up? Is there a certain connector type that I need to look for? Thanks.

[DRJ]

because the brands aren't the same... there are some left wing companies that make adapters though, but I don't trust them, plus they are hard to come by, might as well get a whole new setup, hassle free

[chiefFX4]

Yea, I did a little more research and found that nothing currently on the market is compatible with that head unit. the manual that came with the head unit says to use the sc-c1 with an adapter that is not yet manufactured. searched for it and couldnt find anything. Only site that popped up was crutchfield. contacted them and they said they have no word on release date. part number is CA-LSR01U if anyone knows anything.