You should possibly consider looking at the transformer in two ways; one without a load and one with a load on the secondary.
Without a load on the secondary, the transformer is just an inductor and if you have components (such as L1 and R1) in series with the primary, the voltage developed on the primary will not be the full AC amount from your generator. It's a simple case of calculating the impedances and volt-drops. This is with the secondary unconnected remember.
The primary has inductance like any other coil but, for a transformer to more effective, it is desirable for the primary's self inductance to be high in power applications. If you looked at how much current flowed into the primary (secondary open circuit) you would find that the current was small compared to when driving a load on the secondary and it may have an inductance of several henries.
With 10 henries inductance, at 50Hz the impedance is 3142 ohms and from 230VAC would take a current of 73mA - that current through R1 (10 ohm) hardly drops any voltage.
It's a different matter when there is a load on the secondary. If the turns ratio is 1:1 and you have 100 ohms on the secondary, it is reasonable to argue that the impedance presented to the primary circuit is also 100 ohms. This assumes power out is close to power in. In fact the impedance relationship between primary and secondary is related to turns ratio squared. For instance if it is a 10:1 step-down transformer with a load of 100 ohms, the equivalent impedance at the primary is 10k ohms i.e. 10 x 10 x 100.
In summary, for a power transformer, you'd like the primary inductance to be infinite but that is impractical so you live with something that doesn't take too much current when the secondary is open circuit. The off-load current that flows is real current taken from the AC power and if everyone had low-impedance transformers the electricity companies would be supplying a load of current that doesn't get them revenue. This is a slight exaggeration but not far off the truth. On industrial sites power factor correction is used to minimize this effect but that's a whole new story!
And if your transformer primary was 100 ohm impedance you'd be seeing something less than half your AC voltage applied. If R1 was zero then you'd see exactly half.
As regards saturation I've shown the equivalent circuit of a transformer below. Note that saturation is caused by the current flowing through the magnetizing inductor which is nothing to do with load current: -
Here is a good document from Elliott Sound Products and please note what it says about maximum flux density therefore saturation:
Why doesn't the core saturate more under load conditions? Imagine two coils sharing the same magnetic core. Ignore magnetization currents and losses. The primary is 100 turns and the secondary is 10 turns. If the secondary load current is 10A, the primary current must be 1A and the ampere-turns is therefore the same on both coils. Are these ampere-turns additive or subtractive? They are subtractive and this can easily be seen with dot notation....
If current is flowing into the dot on the primary, current is flowing out of the dot on the secondary and this produces opposing fluxes in the magnetic material. When you think about this you have to be consistent and use the right-hand rule to see that the two fluxes oppose and cancel.
Because the dots are at the top on both coils, they are wound in the same direction and the currents are flowing in (primary) and out (secondary) therefore due to the RH rule the fluxes (due to ampere-turns) are cancelled.
Best Answer
If your transformer has been adequately designed for power applications (50/60 Hz) it will make a poor audio transformer. Ask yourself the question - why does a transformer use laminations - did you know they are insulated from each other so that electrically they don't conduct?
Did you know that if they did all conduct you would have one massive shorted turn?
So, the laminations are there to prevent excessive shorted turns and the thickness might be (say) 1mm and suitable for 50/60 Hz - will that thickness laminate be suitable for 1 kHz - no. You'll get a lot of heating and wasted energy just fighting the eddy currents.
What about coupling factor - a power transformer has (with some hand waving) a coil coupling factor of about ~97%. An audio transformer is much closer to 100%, probably at least 99.5 %. Does this matter? It does at high frequencies because if you added a few tens of milli-henry external to your primary and tried to pass 20 kHz through it you wouldn't get a very good result. That's what happens with leakage inductance - it doesn't couple magnetically to the secondary.
Consider a primary with inductance of 10 H - that's great for 230V AC but the leakage could be 3% of that at 300 mH. At 20 kHz, 300 mH has an impedance of about 38 kohm.
So, if you just want some "near-enough" crappy-fidelity thing with loss of top-end that's fine, use a power transformer.
Those are the dc resistances of the windings and that means your speaker on the secondary is in series with 11 ohms - a lot of power loss there if you have an 8 or 4 ohms speaker.