Question about FiiO BTA30 Pro

Hello

To answer the question, what source are you playing through the BTA 30Pro?
According to your question, you connect the Toslink output of the BTA 30Pro to a Toslink input of the amplifier.
If you want to use the BTA30 Pro without a USB DAC, you need a 5 volt power supply.

I use the iFi Audio iPower MK2 with 5 volts, costs about 75 Fr. today at K55.
But it's worth it for interference-free mains.
If you use the DAC mode, i.e. from the laptop via USB A - C cable to the BTA30 Pro,
the power is supplied by the laptop or PC.

However, you would still have to know how the source plays with regard to the sampling rate.

BTA30 Pro: Digital optical input (TOS / up to 96 kHz / 24 bit)

BTA30 Pro: Digital optical output (TOS up to 192 kHz / 24 bit)

The slight whistling can have several causes.

1. your amplifier can only play a low sampling rate. In this case, you would need to know how high your amplifier can receive?
Your amplifier type?

2. normally Toslink is extremely interference free. However, interference can occur if a Toslink cable is defective.
Cables that are too long can also cause interference.

3. there are also cheap Toslink cables that are not defective, but are not suitable because they are no good. Your Toslink cable?

4. if your source is a music player like iTunes, Winamp or whatever, and your source plays a sampling rate of 24 bit 192 kHz,
there may be interference because the BTA 30Pro can only receive 24-bit 96 kHz.

With Windows 10 / 11, you can check the sound settings to see how it is set.

If you stream via Bluetooth from your mobile to the BTA30 Pro and then play from the Toslink output to the amplifier,
it is possible that there may be interference from the mobile when you pause.

6. mobile phones and Wi-Fi can often interfere with the whole system.

7. is the whistling loud or only soft when paused? Since you have connected both the Cinch and Toslink outputs of the BTA30 Pro to the same amplifier, this can also interfere.
Possibly a ground hum loop?

In this case, disconnect the RCA connection and listen if the interference is gone. If not, then the other way round.

8. if it does not whistle with the cinch output, then listen with this output instead.

I know this and it is very annoying.

But as a rule, a cleanly separated power supply for BTA30 Pro is the best.

Maybe some of this will help?

Otherwise, write down exactly which source you play and which input you need on the BTA30 Pro.
I already know the output.
Then I would need to know which amplifier you need and the exact type?

Greetings Roby

Hi
I connected my BTA30-PRO via cinch to my DENON PMA1510 AE Ultra Hight Current MOS amplifier with 2 old but very good power amps
MAGNAT 655. The BTA30-Pro is controlled via Bluetooth by a Galaxy TAB S8+ 5G. ATTENTION for a very good resolution I use QOBUZ via AUDIRVANA a bit expensive but it is another music. NO NOISE AND GREAT MUSIC watch out for the infamous 10m approx. operational bluetooth
Greetings Dino

Hoi Roby,
thank you very much for your detailed answer!

1. my amplifier or receiver is a Marantz CR603. Unfortunately, they are silent in the manual about the technical data. They only talk about 2 PCM channels. For comparison, I connected the UPC box to the optical input of the Marantz. This way there is no whistling.

2. ok, because of the above point I would exclude this. The cable is 0.75 cm long

3. i bought a "GooBay" here, Digitec says it belongs to the "upper class".

4. I stream via Bluetooth. I use Spotify for this, I hope you're not laughing now. But they also stream at up to 320kBps. The FiiO website says they have a chip that can upsample any signal to 384kHz, but the specs mention 96kHz for optical signals, which you mentioned.
If I stream with Spotify via PC and USB with the DAC mode, then no whistling can be heard. Therefore, I would once again rule out cables and Marantz.

I don't think so, if I turn the volume down really low, the whistling can still be heard.

6. ok.

7. I would have ruled out the ground loop with an optical connection. But I only had one cable plugged in at a time.

8. this will probably be the final solution, but I thought it would be a pity if the signal is not transmitted digitally to the amplifier. obviously optical is not the best quality with the 96 kHz either. My amplifier does not have a coaxial input.

I would have ruled out the power supply problem with the harmonics, as the whistling was also present when I powered the BTA via notebook on the battery and then streamed it with Bluetooth. What do you think?

I also stream to another device (Ruark R1) with Spotify via Bluetooth, and no whistling is audible.

At the moment, my assumption would be that the error occurs from the transition of the Bluetooth chip to the optical output.

However, it would be worth testing another app for streaming.

Hey thanks again, maybe you have some input.

Greetings Christoph