Attenuator recommendations

You might want to get in touch with Marchand Electronics. They have a good selection and can tailor to your needs.

The XLR/RCA presents a difficulty because to be fully balanced means double the components. On the other hand, TVC's don't care about balanced or SE. Either way, you're essentially talking about a passive preamp, in some form.

The Pass amps have a low input impedance that can be difficult for passives but should be good using XLR.

Placette RVC

If you go to www.goldpt.com you will find on page two very detailed explanations about the pros and cons of the resistor types series, ladder stepped and shunt attenuators.In my opinion the ladder stepped type[although more expensive would be the choice]you then get to choose the value and type of resistor also the make of switch.[Vishay and Shallco for me] You could always think about variable transformer tapped types also there are two basic types the auto transformer type such as the sonic euphoria and the switched output tap types like the silver rock and the bent audio there is a massive range of choices and all affect the sound.Among the nicest guys selling all choices of attenuators are Kevin Carter of K+K audio and John Chapman of Bent audio either of these guys will put you on the right track.

It occurs to me that all you need is resistors in male/female adaptors. How's your soldering? You might start with 3 KOhm and see if that works. To give you an idea of the rating, P=V^2/R, so 1 watt would be more than enough. If you can find Vishay at 1% tolerance, you're cookin'. You can't get more direct than that without cutting into the IC's.

RCA requires only one resistor on the positive (inner). XLR needs two. If I'm remembering correctly, (it's been a while) terminals 2 and 3 are hot while 1 is ground.

Why don`t you try passive preamp? TVC is the most recent design and it seems that most owners prefer it at any prize.