I need some techy help in order a preamp--resistor values.

I have owned several khozmo attenuators the best option is with the Vishay Naked resistors shunt remote for only 2 resistors are in the signal path on the output and the Vishay Naked are the lowest distortion and cleanest resistorsfor the application . You just buy it 
complete built it comes with the digital readout board and remote.
for around $400.

I’d check out the same kit avail from diy audio and parts connexion too. I believe they’ve already upgraded the resistors and the Lundahl transformers, which if you’re going to go as far as to build this kit, ya might as well do it right. 🎶🔊🙂

1. First, it's a level control, not a pre-amp.
2. It can also be an input selector.
3. I've used passives and a slew of actives for 40+ years. Each has a sound. Each interacts with cables and associated electronics. There is no free lunch.

SMD resistors have lower inductance and thus have a different sound than leaded parts. However, they require a PCB and a different switch and thus have a different sound.

Each passive topology has its proponents. Each has a different sonic characteristic dependent on the associated components and cables.

Most passives do not compensate for varied amplifier input impedance. Step levels will vary considerably making audition difficult unless one has the tools and skill necessary to match auditioning levels.

1. I've used passives and a slew of actives for 40+ years. Each has a sound. Each interacts with cables and associated electronics. There is no free lunch.

SMD resistors have lower inductance and thus have a different sound than leaded parts. However, they require a PCB and a different switch and thus have a different sound.

Each passive topology has its proponents. Each has a different sonic characteristic dependent on the associated components and cables.

^^ +1!