Is my new SMSL DO100 Pro incompatible with my vintage stereo system?

[Xcollx]

I'm having problems with my new DAC on my vintage stereo system. Speakers sound is very thin (no bass). I'm connected by Bluetooth and trying to play files from Mac Music.

It's not a power issue: The DAC is connected with RCA cables to a Hafler preamp (which only has RCA inputs) that's connected to a powerful Adcom GFA-555 amp driving big Polk ADA-2 speakers. I've tried changing filters and settings but nothing changes the terrible sound. I'm wondering if I should just return the DAC as incompatible. Any suggestions?

 

[MaxwellsEq]

vintage stereo system.

Short answer - you probably need to attenuate the signal entering your Hafler preamplifier.

Longer answer: many vintage systems (I bought HiFi before CD was invented) expect a peak line in level of 1V. This was the level produced by reel to reel and cassette tape players and also tuners. CD and more recently DACs produce 2V from very first players onwards. Some produce more than 2V. I had preamplifiers built in the late 70s which sounded bad with CD players, so I had to build attenuators to lower the level ahead of the preamplifier.

Alternatively, give up on the vintage gear, apart from nostalgia and looks it has no real benefit and often many downsides. Well designed modern amplifiers perform better.

 

[Xcollx]

Thank you – how does one attenuate the signal?

 

[Mnyb]

Somekind if inline atenuators in series with the cables .

se this brand as an example ( bougth from them 20 years ago web page loks exactly the same , maybe Amazon could produce something similar but cheaper and easier to order )

Attenuators

 

[Xcollx]

Not being a techie, I find it confusing that attenuators are rated by dB levels but my preamp line output is in Vrms. Its specs list numbers like Rated Output: 3 Vrms, 4 Hz-210 kHz, Maximum Output (3.5): 14 Vrms, 20 Hz-20 kHz, Maximum Input Signal @ 1 kHz (3.8): 14 Vrms, Gain: 20 dB ± 1 d B, Input Impedance: Greater than 25,000 ohms.

What would be the specs that have to match up for normal function of my system via bluetooth DAC with or without attenuators?