Inverse Fourier transform of sinc function

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I'm trying to find the input of an LTI system.

So far I'm at the point where I know

$$ X(f) = \frac{sin(2\pi f)}{\pi f}$$

I also know that a $$sinc(t) = \frac{sin(\pi f)}{\pi f}$$

And the Fourier transform table says that:

$$ x(t) = rect(\frac{t}{\tau}) <=> X(f) = \tau sinc(\tau f)$$

I having trouble getting my $X(f)$ into the proper form to be converted into the time domain.

My attempt is this:

$$ X(f) = \frac{sin(2\pi f)}{\pi f} * \frac{2}{2}$$

$$ X(f) = 2\frac{sin(2\pi f)}{2\pi f} $$

$$ X(f) = 2{sinc(2 f)} $$

$$ X(f) = \tau {sinc(\tau f)} $$

$$ X(t) = rect(\frac{t}{\tau}) $$

$$\tau = 2$$

Therefore: $$x(t) = rect(\frac{t}{2})$$

But I feel like I'm making a mistake. Any thoughts? Thanks.